This is day 3 of me battling the same problem and I'm getting to the conclusion that this may not be me doing something wrong but maybe there is something wrong with the Unreal Live Link.
Look at the image.
I've now tried 2 different helmets, 3 different textures.
I've tried to send the helmet and visor as part of the Avatar and I've tried to send the helmet and visor as props linked to the avatar.  All of them had problems.
The normals are messed up and the entire textures of the head looks horrible too.  Look at the face in UE.  It looks the same with the HQ shader.