I have some geometry, in my model, that will not render materials. I have tried the most basic material, with just a diffused color, and it only renders gray. I exported the geometry, and brought it back in, but nothing! Any clues?
Normal?
Create new geometry and merge to it…
Check mixer see if visibiliyu ios 1 or 0.5 etc…
Check mixer see if visibiliyu ios 1 or 0.5 etc…can you explain?
visibiliy is 1
Just a guess but maybe a vray override mtl in the Global switches?
Yeah, I once also searched for quite some time why this particular object won´t change no matter what I do until I realized I had “override” turned on
and most other objects excluded. 
If this is not the case you can try to extract the Geometry with a “Mesher” Object. This usually helps. I remember getting CAD geometry from a customer
and it just won´t accept Mapping coordinates. A Mesher solved the problem in my case.
As extreme make over u can use Particles to recreate quickly geometry and then mesh it back in to edit poly… weird work around but should fix even the most bizarre issues…