Hi, thanks a lot for your reply. I have already watched Winbush’s video, but actually he is using a premade Mixamo rig which seems to work fine. One of my colleges has tried my attempt with Blender, which seems to be a lot less trouble but switching to Blender unfortunatelly is not an option. I have also tried the freezing that you suggested but this didn’t change anything. I have absolutely no idea what I’m doing wrong here 
Do you know why Datasmith does not take bones into account? This would probably make the process a lot easier.