As well as assigning a new animation, are you also swapping out the characters model?
Yes, we are swapping out the whole model. We made sure to assign the new model first before assigning the new animation, but does there need to be a small delay, to maybe make sure the new model is properly initialized?
I also found this post about Not assigning an animation breaks the new anim component just now. In there you said:
The anim component is indeed inactive if any of it’s states are unset.
Could this maybe relate to this issue? I’m making sure that all states actually have an animation linked, but maybe the component thinks some of them are empty?