Groom alligns to "grid" after bind

I’ve encountered this bug when trying to bind a groom to our character.

This is how it should look

This happens after the bind

The groom binds perfectly well to the unskinned head without morph targets. It also binds without issue to the skinned version WITHOUT the morph targets and also to an unskinned version WITH Morph Targets.
The combination of both seams to create some issues. We also tried to reduce the MT number but the outcome was the same.

For context the head has 290 morph targets if that should be relevant. Also not only the eyebrow area has those artefacts. Every groom bound to the head gets that grid pattern.

I am curious if someone else also had similiar issues or can give us a notch in the right direction