Lark can't match µ character even though it is defined in the input

[adi12345-crypto]

I am trying to write a lark parser which can extract parts of text of form number unit e.g 10 grams or 10gm etc. I am trying to parse the following input:
"10 μl"
I get the error
`10 μl
^
Expected one of:
* DECIMAL_HAHNEMANNIAN
* WEIGHT_GM
* DOSIS_TABLET
* WEIGHT_MG
* LENGTH_CM
* CELL_CULTURE_INFECTIOUS_DOSE
* MILLION_COLONY_FORMING_UNIT
* WEIGHT_NG
* SEPARATOR
* MICROKATAL
* SPEYWOOD_UNIT
* DOSIS_BLISTER
* DOSIS_GENERATOR
* VOLUME_L
* EFFECTIVE_RESPONSE_50
* EFFECTIVE_RESPONSE_60
* WEIGHT_MCG_BASE
* TISSUE_CULTURE_INFECTIOUS_DOSE
* SPACES
* VOLUME_ML
* HIGH_ACTIVATION_UNIT
* ANTIGENIC_UNIT
* LOG_ELISA_UNIT
* EFFECTIVE_RESPONSE_25
* MILI_EQUIVALENTS_UNIT
* BECQUEREL
* BIOEQUIVALENT_ALLERGY_UNIT
* DOSIS_SRT
* HOMEOPATHIC_POTENCY_C_UNIT
* IU_MIU
* DOSIS_GUM
* MOLE_MCMOL
* TIME_MIN
* GIGA_BECQUEREL
* HAEMAGGLUTINATION_INHIBITION_UNIT
* PERCENT
* DOSIS_BAG
* DOSIS_PACK
* VECTOR_GENOME_UNIT
* ANTI_XA_UNIT
* ALLERGAN_UNIT
* PROTEIN_NITROGEN_UNIT
* PERCENT_WEIGHT_PER_WEIGHT
* IU_IU
* TIME_DAY
* MOLE_MOL
* MILLION_CELL
* HOMEOPATHIC_POTENCY_X_UNIT
* DOSIS_CAPSULE
* MICROCURIE
* DOSIS_DOS
* D_ANTEGEN_UNIT
* GALACTOSIDASE_UNIT
* DOSIS_CONTAINER
* WEIGHT_PG
* KATAL
* WEIGHT_LBS
* VOLUME_DROP
* GERMS_UNIT
* CELL
* ANTIBODY_MICRO_AGGLUTINATION_LYTIC_REACTION_UNIT
* LOG_TISSUE_CULTURE_INFECTIOUS_DOSE
* TIME_HOUR
* HOMEOPATHIC_POTENCY_M_UNIT
* WEIGHT_MG_BASE
* LENGTH_MM
* OOCYST_UNIT
* RELATIVE_POTENCY_UNIT
* VOLUME_MCL
* KALLIDINOGENASE_INACTIVATOR_UNIT
* IU_KIU
* PERCENT_VOLUME_PER_VOLUME
* KALLIKREIN_INACTIVATOR_UNIT
* PERCENT_WEIGHT_PER_VOLUME
* LIMIT_OF_FLOCCULATION_UNIT
* EFFECTIVE_RESPONSE_120
* WEIGHT_TON
* WEIGHT_MCG
* LOG_CELL_CULTURE_INFECTIOUS_DOSE
* PARTS_PER_MILLION_UNIT
* TCP_UNIT
* HOMEOPATHIC_POTENCY_Q_UNIT
* DOSIS_KIT
* KILO_BECQUEREL
* WEIGHT_KGS
* TUBERCULIN_UNIT
* MILICURIE
* LOG_HAEMAGGLUTINATION_INHIBITION_UNIT
* DOSIS_LOZENGE
* RANGE_SEPARATOR
* MEGA_BECQUEREL
* USP_UNIT
* FLUORESCENT_FOCUS_UNIT
* DOSIS_SACHET
* DOSIS_BOTTLE
* EQUIVALENTS_UNIT
* ELISA_UNIT
* PERCENT_VOLUME_PER_WEIGHT
* DOSIS_VIAL
* SPORULATED_OOCYST_UNIT
* COLONY_FORMING_UNIT
* PULSATION_UNIT
* MOLE_MMOL
* CURIE
* AREA_CM_SQ
* DOSIS_STRIP
* BILLION_COLONY_FORMING_UNIT
* HOMEOPATHIC_POTENCY_UNIT
* PLAQUE_FORMING_UNIT
* WEIGHT_GM_BASE
* LOG_COLONY_FORMING_UNIT
* MOLE_NMOL
* DOSIS_SYRINGE
* DOSIS_CARTRIDGE
* EFFECTIVE_RESPONSE_70
* DOSIS_ACT
* DOSIS_CYLINDER
* LOG_PLAQUE_FORMING_UNIT
* VOLUME_GAL
* DOSIS_PIECE

NoneMy token VOLUME_MCL is defined as:
VOLUME_MCL: "mikroliter" | "microl" | "mcl" | "µl" | "ul"
`

[adi12345-crypto]

For reference here is the grammar:

// define rules for strength and strength ranges when they appear alone and with additional text
start: strength_only | strength_range_only | strength_additional_text
| strength_range_additional_text | concatenated_strengths_only
| words_only

// define structure for rules with no additional text
strength_only.2: number unit | number unit? separator number? unit
concatenated_strengths_only.2: strength_only concatenator strength_only
strength_range_only.2: strength_only range_separator strength_only | number range_separator number unit
// define structure for rules with additional text
strength_additional_text: (skippable* strength_only skippable*)+
strength_range_additional_text: (skippable* strength_range_only skippable*)+
// define structure for words only
words_only: extended_word+

// define non-terminals units as all possible unit rules then for each unit rule specify units
unit: base_unit | base_unit separator base_unit
base_unit.2: weight_unit | limit_of_flocculation_unit | volume_unit | length_unit | mole_unit | iu_unit
| percent_unit | time_unit | percent_weight_volume | dosis_unit | colony_forming_unit
| kallikrein_inactivator_unit | plaque_forming_unit | becquerel_unit | cell_unit | area_unit
| curie_unit | tissue_culture_infectious_dose_unit | hahnemannian_unit | parts_per_million_unit
| vector_genome_unit | anti_xa_unit | cell_culture_infectious_dose_unit | equivalents_unit | d_antegen_unit
| elisa_unit | allergan_unit | effective_response_unit | relative_potency_unit | tcp_unit
| haemagglutination_inhibition_unit | oocyst_unit | high_activation_unit | antigenic_unit
| tuberculin_unit | antibody_micro_agglutination_lytic_reaction_unit | speywood_unit | galactosidase_unit
| pulsation_unit | katal_unit | germs_unit | kallidinogenase_inactivator_unit | usp_unit
| homeopathic_potency_unit | bioequivalent_allergy_unit | fluorescent_focus_unit | protein_nitrogen_unit

// define all weight units
weight_unit: WEIGHT_TON | WEIGHT_KGS | WEIGHT_KGS | WEIGHT_LBS | WEIGHT_GM | WEIGHT_GM_BASE | WEIGHT_MG
| WEIGHT_MG_BASE | WEIGHT_MCG | WEIGHT_MCG_BASE | WEIGHT_NG | WEIGHT_PG
WEIGHT_TON: "tonelada" | "tons" | "ton" | "tne" | "mts"
WEIGHT_KGS: "kilograms" | "kilogramm" | "Kilogramm" | "kilogram" | "kilo" | "kgs" | "kgm" | "kga" | "kg"
WEIGHT_LBS: "lbs"
WEIGHT_GM: "gramm" | "grams" | "gramo" | "gram" | "gms" | "gm" | "g." | "g"
WEIGHT_GM_BASE: "g base"
WEIGHT_MG: "milligramm" | "mili.gram" | "miligramo" | "milig" | "mgs" | "mg"
WEIGHT_MG_BASE: "mg base"
WEIGHT_MCG: "micrpgrammes" | "microgrammes" | "microgramme"| "mikrogramm" | "microgramo"
| "mikrograma" | "mikrogramów" | "microgram" | "microg" | "mcg" | "µg" | "ug"
WEIGHT_MCG_BASE: "mcg base"
WEIGHT_NG: "nanogramm" | "ng"
WEIGHT_PG: "picogramm"

// define all volume units
volume_unit: VOLUME_GAL | VOLUME_L | VOLUME_DROP | VOLUME_ML | VOLUME_MCL
VOLUME_GAL: "gal"
VOLUME_L: "liter" | "l"
VOLUME_DROP: "drop"
VOLUME_ML: "millilitre" | "milliliter" | "ml"
VOLUME_MCL: "mikroliter" | "microl" | "mcl" | "µl" | "ul"

// define all length units
length_unit: LENGTH_MM | LENGTH_CM
LENGTH_MM: "millimeter" | "mm"
LENGTH_CM: "zentimeter" | "cm"

//define all mole units
mole_unit: MOLE_NMOL | MOLE_MMOL | MOLE_MCMOL | MOLE_MOL
MOLE_NMOL: "nanomol" | "nmol"
MOLE_MMOL: "millimol" | "mmole" | "mmol"
MOLE_MCMOL: "micromol" | "mcmol" | "µmol"
MOLE_MOL: "mole" | "mol"

// define all iu units
iu_unit: IU_IU | IU_KIU | IU_MIU
IU_IU: "internationale einheit(en)" | "internationale einheit" | "pressor units" | "unités" | "u.i."
| "i.u." | "i.e." | "unit" | "u." | "iu" | "[iu]" | "j.m." | "ie" | "ui" | "u"
IU_KIU: "kilo UI" | "kiu"
IU_MIU: "million international units (iu)" | "millones ui" | "millions ui" | "million i.e." | "mill. ui"
| "million u" | "m.ui" | "miu" | "mu"

// define all percent units
percent_unit: PERCENT
PERCENT: "porcentaje" | "porciento" | "%"

// define all time units
time_unit: TIME_MIN | TIME_HOUR | TIME_DAY
TIME_MIN: "min"
TIME_HOUR: "hour" | "h"
TIME_DAY: "day"

// define all percent weight volume units
percent_weight_volume: PERCENT_WEIGHT_PER_WEIGHT | PERCENT_WEIGHT_PER_VOLUME
| PERCENT_VOLUME_PER_VOLUME | PERCENT_VOLUME_PER_WEIGHT
PERCENT_WEIGHT_PER_WEIGHT: "% (w/w)" | "% w/w" | "% / w/w" | "%w/w" | "porcentaje peso/peso"
PERCENT_WEIGHT_PER_VOLUME: "% / w/v" | "% w/v" | "% (w/v)"
PERCENT_VOLUME_PER_VOLUME: "prozentgehalt volumen in volumen" | "% / v/v" | "% v/v" | "% (v/v)"
PERCENT_VOLUME_PER_WEIGHT: "Prozentgehalt Volumen in Masse"

// define all dosis units
dosis_unit: DOSIS_DOS | DOSIS_VIAL | DOSIS_BAG | DOSIS_BOTTLE | DOSIS_SACHET | DOSIS_SYRINGE| DOSIS_CONTAINER
| DOSIS_SRT | DOSIS_ACT | DOSIS_GUM | DOSIS_BLISTER | DOSIS_STRIP | DOSIS_CAPSULE
| DOSIS_KIT | DOSIS_TABLET | DOSIS_PACK | DOSIS_LOZENGE | DOSIS_CARTRIDGE | DOSIS_PIECE | DOSIS_GENERATOR
| DOSIS_CYLINDER
DOSIS_DOS: "dawkę odmierzoną" | "dos(es)" | "dose(s)" | "dosis" | "dose" | "dos"
DOSIS_VIAL: "flacon" | "fiolkę" | "vial"
DOSIS_BAG: "bag" | "zak"
DOSIS_BOTTLE: "bottle"
DOSIS_SACHET: "sachet"
DOSIS_SYRINGE: "syr"
DOSIS_CONTAINER: "container"
DOSIS_SRT: "srt"
DOSIS_ACT: "act"
DOSIS_GUM: "gum"
DOSIS_BLISTER: "blister"
DOSIS_STRIP: "strip" | "pasek"
DOSIS_CAPSULE: "capsules" | "capsule" | "cap"
DOSIS_KIT: "kit"
DOSIS_TABLET: "tablet" | "tab"
DOSIS_PACK: "pck"
DOSIS_LOZENGE: "loz"
DOSIS_CARTRIDGE: "cartridge"
DOSIS_PIECE: "stück" | "piece" | "stuk"
DOSIS_GENERATOR: "gen"
DOSIS_CYLINDER: "cylr"

// list all colony forming units
colony_forming_unit: COLONY_FORMING_UNIT | LOG_COLONY_FORMING_UNIT
| MILLION_COLONY_FORMING_UNIT | BILLION_COLONY_FORMING_UNIT
COLONY_FORMING_UNIT: "koloniebildende einheit(en)" | "cfu" | "[cfu]"
LOG_COLONY_FORMING_UNIT: "log10 cfu"
MILLION_COLONY_FORMING_UNIT: "millionkeime" | "million cfu"
BILLION_COLONY_FORMING_UNIT: "b"

// list all kallikrein inactivator units
kallikrein_inactivator_unit: KALLIKREIN_INACTIVATOR_UNIT
KALLIKREIN_INACTIVATOR_UNIT: "kallikrein-inhibitor-einheit" | "kui"

// list all plaque forming units
plaque_forming_unit: PLAQUE_FORMING_UNIT | LOG_PLAQUE_FORMING_UNIT
PLAQUE_FORMING_UNIT: "unidades formadoras de placa (ufp)" | "pfu" | "[pfu]"
LOG_PLAQUE_FORMING_UNIT: "log10 pfu"

// list all becquerel unit
becquerel_unit: BECQUEREL | KILO_BECQUEREL | MEGA_BECQUEREL | GIGA_BECQUEREL
BECQUEREL: "becquerel"
KILO_BECQUEREL: "kilobequerelio" | "kbq"
MEGA_BECQUEREL: "megabecquerelio" | "megabecquerel" | "mbq"
GIGA_BECQUEREL: "gigabecquerelios" | "gigabecquerel" | "gbq"

// list all cell unit
cell_unit: CELL | MILLION_CELL
CELL: "celulas" | "komorek" | "cellen" | "cells"
MILLION_CELL: "millions de cellules" | "million cells" | "mln komórek"

// list all area unit
area_unit: AREA_CM_SQ
AREA_CM_SQ: "quadratzentimeter" | "sq cm" | "cm2"

// list all currie unit
curie_unit: CURIE | MILICURIE | MICROCURIE
CURIE: "ci"
MILICURIE: "mci" | "millicurie"
MICROCURIE: "mcci" | "mikrocurie"

// list all tissue culture infectious dose unit
tissue_culture_infectious_dose_unit : TISSUE_CULTURE_INFECTIOUS_DOSE | LOG_TISSUE_CULTURE_INFECTIOUS_DOSE
TISSUE_CULTURE_INFECTIOUS_DOSE: "gewebekultur-infektiöse-dosis 50%" | "tcid50" | "[tcid_50]"
LOG_TISSUE_CULTURE_INFECTIOUS_DOSE: "log10 tcid50"

// list all hahnemannian units
hahnemannian_unit: DECIMAL_HAHNEMANNIAN
DECIMAL_HAHNEMANNIAN: "dh"

// list all ppm units
parts_per_million_unit: PARTS_PER_MILLION_UNIT
PARTS_PER_MILLION_UNIT: "ppm" | "[ppm]"

// list all vector_genome units
vector_genome_unit: VECTOR_GENOME_UNIT
VECTOR_GENOME_UNIT: "vg"

// list all anti xa unit
anti_xa_unit: ANTI_XA_UNIT
ANTI_XA_UNIT: "anti-blutgerinnungsfaktor xa aktivität" | "anti xa units" | "u.i. antixa" | "ui anti-xa"
| "ul anti-xa" | "anti-xa iu" | "anti-xa ui" | "ui antixa" | "anti-xa" | "j.m. a.xa"
| "unidades antigenicas"

//list all cell_culture_infectious_dose unit
cell_culture_infectious_dose_unit: CELL_CULTURE_INFECTIOUS_DOSE | LOG_CELL_CULTURE_INFECTIOUS_DOSE
CELL_CULTURE_INFECTIOUS_DOSE: "ccid50" | "cid50"| "[ccid_50]"
LOG_CELL_CULTURE_INFECTIOUS_DOSE: "log10 ccid50" | "log10 cid50"

// list all equivalents unit
equivalents_unit: EQUIVALENTS_UNIT | MILI_EQUIVALENTS_UNIT
EQUIVALENTS_UNIT: "eq"
MILI_EQUIVALENTS_UNIT: "meq"

// list all d antegen units
d_antegen_unit: D_ANTEGEN_UNIT
D_ANTEGEN_UNIT: "unités antigènes d" | "D-UNITS" | "[d'ag'u]" | "d-au" | "du"

// list all elisa unit
elisa_unit: ELISA_UNIT | LOG_ELISA_UNIT
ELISA_UNIT: "elisa unit" | "elisa u" | "u elisa"
LOG_ELISA_UNIT: "log10 elisa u"

// list all all alergan unit
allergan_unit: ALLERGAN_UNIT
ALLERGAN_UNIT: "allergan-einheit"| "allergen-einheit" | "alergen units" | "allergan unit" | "Allergan units"
| "[au]" | "au"

// list all effective response
effective_response_unit: EFFECTIVE_RESPONSE_25 | EFFECTIVE_RESPONSE_50 | EFFECTIVE_RESPONSE_60 | EFFECTIVE_RESPONSE_70
| EFFECTIVE_RESPONSE_120
EFFECTIVE_RESPONSE_25: "% er25"
EFFECTIVE_RESPONSE_50: "% er50"
EFFECTIVE_RESPONSE_60: "% er60"
EFFECTIVE_RESPONSE_70: "% er70"
EFFECTIVE_RESPONSE_120: "% er120"

// list all relative potency unit
relative_potency_unit: RELATIVE_POTENCY_UNIT
RELATIVE_POTENCY_UNIT: "rp"

// list all tcp unit
tcp_unit: TCP_UNIT
TCP_UNIT: "tcp units"

// list all haemagglutination_inhibition_unit
haemagglutination_inhibition_unit: HAEMAGGLUTINATION_INHIBITION_UNIT | LOG_HAEMAGGLUTINATION_INHIBITION_UNIT
HAEMAGGLUTINATION_INHIBITION_UNIT: "hai" | "hiu"
LOG_HAEMAGGLUTINATION_INHIBITION_UNIT: "log10 hai" | "log10 hi" | "log10 hiu"

// list all oocysts unit
oocyst_unit: OOCYST_UNIT | SPORULATED_OOCYST_UNIT
OOCYST_UNIT: "oocysts"
SPORULATED_OOCYST_UNIT: "sporulated oocysts"

// list all high activation unit
high_activation_unit: HIGH_ACTIVATION_UNIT
HIGH_ACTIVATION_UNIT: "hau"

// list all antigenic unut
antigenic_unit: ANTIGENIC_UNIT
ANTIGENIC_UNIT: "antigenic units" | "unidades antigénicas"

// list all tuberculin_units
tuberculin_unit: TUBERCULIN_UNIT
TUBERCULIN_UNIT: "tu"

// list all antibody_micro_agglutination_lytic_reaction unit
antibody_micro_agglutination_lytic_reaction_unit: ANTIBODY_MICRO_AGGLUTINATION_LYTIC_REACTION_UNIT
ANTIBODY_MICRO_AGGLUTINATION_LYTIC_REACTION_UNIT: "alr"

// list all speywood unit
speywood_unit: SPEYWOOD_UNIT
SPEYWOOD_UNIT: "unités speywood" | "speywood units"

// list all galactosidase_units
galactosidase_unit: GALACTOSIDASE_UNIT
GALACTOSIDASE_UNIT: "galu"

// list all pulsation units
pulsation_unit: PULSATION_UNIT
PULSATION_UNIT: "pulsación"

// list all katal unit
katal_unit: KATAL | MICROKATAL
KATAL: "katal" | "katals"
MICROKATAL: "microkatals" | "mikrokatal"

// list all limit_of_flocculation_unit
limit_of_flocculation_unit: LIMIT_OF_FLOCCULATION_UNIT
LIMIT_OF_FLOCCULATION_UNIT: "lf"

// list all germs unit
germs_unit: GERMS_UNIT
GERMS_UNIT: "keime"

// list all kallidinogenase_inactivator_unit
kallidinogenase_inactivator_unit: KALLIDINOGENASE_INACTIVATOR_UNIT
KALLIDINOGENASE_INACTIVATOR_UNIT: "kallidinogenase-inaktivator-einheit"

// list all usp unit
usp_unit: USP_UNIT
USP_UNIT: "usp-einheiten" | "[usp'u]" | "[usp]"

homeopathic_potency_unit: HOMEOPATHIC_POTENCY_UNIT | HOMEOPATHIC_POTENCY_X_UNIT | HOMEOPATHIC_POTENCY_C_UNIT
| HOMEOPATHIC_POTENCY_M_UNIT | HOMEOPATHIC_POTENCY_Q_UNIT
HOMEOPATHIC_POTENCY_UNIT: "hp"
HOMEOPATHIC_POTENCY_X_UNIT: "[hp_x]"
HOMEOPATHIC_POTENCY_C_UNIT: "[hp_c]"
HOMEOPATHIC_POTENCY_M_UNIT: "[hp_m]"
HOMEOPATHIC_POTENCY_Q_UNIT: "[hp_q]"

// list all bioequivalent_allergy_units
bioequivalent_allergy_unit: BIOEQUIVALENT_ALLERGY_UNIT
BIOEQUIVALENT_ALLERGY_UNIT: "[bau]"

// list all fluorescent_focus_units
fluorescent_focus_unit: FLUORESCENT_FOCUS_UNIT
FLUORESCENT_FOCUS_UNIT: "[ffu]" | "ffu"

// list all protein_nitrogen_units
protein_nitrogen_unit: PROTEIN_NITROGEN_UNIT
PROTEIN_NITROGEN_UNIT: "[pnu]" | "pnu"

// list all helper terminals used to define strength rules
not_important: extended_word | ignorable_special_chars
skippable: not_important+
spaces: SPACES*
extended_word: spaces* EXTENDED_WORD spaces*
ignorable_special_chars: spaces* IGNORABLE_SPECIAL_CHARS spaces*
number.2: spaces* NUMBER spaces*
separator.2: spaces* SEPARATOR spaces*
concatenator.2: spaces* CONCATENATOR spaces*
range_separator.2: spaces* RANGE_SEPARATOR spaces*

// define general terminals
EXTENDED_WORD: /[a-zA-ZöäüéÖÄÜß]+/
IGNORABLE_SPECIAL_CHARS: /[,.;:-[]()+&%*]/
SEPARATOR: "in" | "per" | "\" | "/" | "per dose of"
CONCATENATOR: "+" | ","
RANGE_SEPARATOR: "-" | "–" | "to"
NUMBER: /\d+([ \s.,]\d*)*|[.,]?\d+([eE^xX][-]?\d+)?/
SPACES: /\s+/

any tips on improving the grammar are also aprreciated :)