Mecanim in Unity, issues with bones automapper

Mecanim in Unity - very powerful feature with automatic bones detection and retargeting introduced 4 years ago. What could go wrong?

Mecanim in Unity - very powerful feature with automatic bones detection and retargeting introduced 4 years ago. What could go wrong?

Look at next image: bone names are correct, hierarchy valid, but unity automapper says that there are no Chest bone (arms detected correctly too):

I spent 2 hours in multiple tests and fixed issue:

But you can say “it looks same”! Yes, but not for unity bones mapper: Chest bone now slightly longer than Spine bone and mapper marks it as real Chest bone.

Btw, this behaviour was described in unity blog post at “Bone Length Ratios” part. But hey, why I should calculate bone lenghts at all?!

Shame on you, “Mecanim devteam” for this idea and no any warnings during import - bone names should be prefered over bone lenghts!