Animation Overrides Controller does not use AvatarMasks on Layer

In my current project I change the animation controller at runtime. There is a basic animator that is configured with multiple layers and state machines. One layer has an avatar mask. When the animation controller is changed to an animator override controller at runtime, this mask is not applied anymore. Only when I change back to the original animator the mask is applied again.

The animation used in the animation override controller are pretty similar to the original controller. I think this might be a bug.