spr.drawString jiggles around when displaying Strings with EVEN amount of digits but not ODD

[dentaku-web]

I've noticed that when I use spr.setTextDatum(MC_DATUM);
then do something like this in my loop, where int32_t num1 is the value of a rotary encoder and he font is consolab24.vlw stored in Flash using LittleFS
spr.drawString(String(num1), 32, 32);

The numbers will stay still just fine when I'm displaying 0 through 9 but once I get into 2 digit numbers they jiggle left and right as the second digit pushes the first one around. I'm assuming they're trying to stay centred according to how MC_DATUM works.
In fact, any String with any EVEN number of digits does this but ODD numbers of digits don't jiggle.

Using ML_DATUM and shifting the x position a gives me perfectly stable results as the number changes but of course I want to use MC_DATUM.

Previously I was using spr.drawNumber with "consolab12pt7b.h" where MC_DATUM was solid and the characters stayed in place but I wanted to know how much better it would look using .vlw fonts.

[dentaku-web]

Well, I seem to have figured it out. For some reason I thought spr.drawNumber didn't work while using this type of font so I switched to spr.drawString but it turns out it DOES work.
Now my numbers stay in place when using MC_DATUM which is much handier that having to use ML_DATUM then figuring out haw many pixels I need to nudge everything on the x axis to make it centred.
Now I'm wondering why spr.drawNumber and spr.drawString handle MC_DATUM differently?