Override blending making shadows look bad?

Hi,

I've go character with humanoid animations on one layer and facial expresions on second layer. If my facial expresions are humanoid and I use override blending not ony I change facial expresion but head position. If I use additive blending not every facial animation is working (dont' know why). I change facial expressions to generic and assing transform in avatar mask. Now in override blending only facial expression is change, so it is what I want, but shadows change as well, and I have no idea why.


Base layer humanoid, facial layer generic, blending override
weight 0



weight 1




Thanks for your advices!