Wierd/Wrong import of COLLADA (.dae ) files

[nicolamarella]

Hello,
I am currently using the UnityMeshImporter project which basically wraps assimp-net for Unity, to import at runtime a COLLADA file, but for some reason, the import seems to be all messed up.
I've tried using the Unity editor to import del file, here is the exptected result:

Yet, when I use the importer at runtime, this is the result:

Wierdly enough, some other .dae files get imported correctly, for example the anymal_thigh_r.dae attached to this issue get imported correctly.

I've tried different extension of the same file, for example .obj and .ply, which seems work to but I cannot get the vertex colors rendered in that case (feature I need)

Attached to this issue there is also the file used in the screenshot. As I am quite new to working with 3D files, I have very little clue on what might be issue.

Here are the meshes that causes the wierd behaviour:
meshes.zip

Thanks in advance