Eye White disappearing when angling up

I don't why this is happening. I never encountered this issue on this model before.

Link to images on the issue
https://imgur.com/a/9BeMmCF

For additional info, the face parts were originally merged together (was given to me that way)

On this other version, I decided to separate them and now this happens.

I checked the blender file and there was no issue like this on the model.

How do I fix this?

 

It looks like when you separated the meshes you may have destroyed the proper vertex group settings on the eye mesh itself and now the model is clipping with itself.

 

Can I easily fix that or do I revert to the version with all them grouped up?

 

I guess the best question is "why did you do this in the first place?"

 

Your model has a surface that goes parallel to the eyes and follows their shape closely.. When eyes go to far up, they start clipping through it.
Remove that surface or push it inside the head, creating an "eye socket".

I also don't understand why the heck did you try to separate them, when the original version worked properly. For an anime head having separate eyes is rather pointless.

 

Well... It was tedious to retexture the head parts after auto-rigging from mixamo. When I "Select All Faces (L)" one face part, it selects every part of the head and not, say, the pupil.

I haven't figured out how to auto-rig with the textures in it. When I try, mixamo does not accept the fbx file so I was forced to auto-rig it with no texture.

Lessons learned, I suppose...

 

You could select parts you do not want in mesh edit mode, and simply hide them with "H".