[Maya/Vray] - Select objects are black in viewport and render

So this is a head scratcher for me…

I have CAD data which I optimized and deshelled (bendy tube that is a “shell” or solid). I then unwrapped the optimized and deshelled CAD mesh. Then I extruded that mesh to make it a solid once more (shell) and to copy the UV map from the outer to inner shell…

Now however, the object is black in the viewport and it renders black. Normals are correct (no backface culling). I’ve attempted to delete all history, weld all verts (to make sure it was a tight mesh), export to OBJ/FBX and then import those exports (obj doesn’t retain UV coordinates so defeats the purpose), but still no joy.

What could be the cause of this? Bad geo, yeah, but what does that mean in this case? Any recommendations on how to fix this mesh? If interested I could upload the mesh for anyone willing to take a look at it.

Stupid and frusterating as I want those damn UVs (took a while to unwrap those bastards).

Thanks much for any advice.

update: Something weird in Maya. That’s the best I have… I had a friend take the FBX and do the good ol’ box trick in 3ds max. Worked a charm.