Error instantiating animated prefab from asset bundle in the editor

I'm having a weird issue. This used to work without any issues, and now it's not. I have no idea what changed that could have impacted that. When instantiating an animated prefab from an asset bundle I get the following error, and no animations play:
The Animator Controller (Prefab Name) you have used is not valid. Animations will not play

This only impacts the editor though, it still works in a build. Any ideas on how to resolve this?

 

me too