Why my animation isn't working with Mecanim

I've got a character rigged and animated, imported as FBX into unity. Using mecanim, everything works fine, but one of the bones is broken. One of the bones in the hand isn't rotating/moving at all for some reason. Every other part seems fine and works the way I want them to.

The animations works perfectly in the preview box.

The animations works perfectly if I just remove the Animator and add an "Animation" instead (Legacy).

This is my setup:

Type: Generic

Avatar: Created from this model

Exported with Maya FBX Exporter, every keyframe is baked