Unreal crashed after adding animation key

I have a problem, where Unreal crashes after adding an animation key. It crashes the moment i hit apply.

I noticed two thing though:

  1. The problem only accours with retargeted animations. If, for example, i create an animation through the recording function, i can add animation keys for every bone without problems.
  2. The problem only occours with specific bones. In my case these are bones, which control the armour of the character.
    It seems, that every bone, that wasn’t in the original model, the animation was retargeted from, causes trouble.

It would be very annoying, if i can’t use retargeted animations properly, because of this. Does anyone know how to solve this problem?