Imported model has weird errors.

Unity Engine
1

Hello,
I recently commissioned a model to be made for my game project. however, once I imported the Maya file that I was given, the model has very strange errors.

Geometry becomes invisible in some angles, some things become see through, and weirder of all, the model’s right eye moves according to the camera/becomes invisible/flat when it’s put in any shader OTHER than toon (It works just fine if its toon basic) if i put it on diffuse or something else it starts acting very weird.
Here’s a picture of what’s happening.

as you can see, the eye is different in the angles, and it moves according to camera(?)

2

It might be difficult to tell, but does it look as though the models are inside out (ie, as if you are seeing the inner surface of the back of the model)? If so, it may be a problem with normals. Unfortunately, I’ve no idea how you could fix this in Maya, but it might give you something to go on.