Question Problem with animation of instantiated prefabs

Hi,

I have a model from Blender with one armature and I'm instantiating it during runtime four times and then parent the four gameobjects to one single transform. I also add a rig and a rig layer during runtime. I also add constraints like MultiAimConstraint for all four armatures (from the same model so they all have the same avatar).

The first instantiated object is animating fine as expected. But the other three or not animating at all. I can make their parts move if i manipulate the bones by hand in the editor, but the rig is not doing anything on them.

Does anyone know what might be the problem here?

I'm using Unity 2021.1.1.0b8 and Animation Rigging package 1.0.3.

Thank you
Slowin