I’m currently using V-ray for my rendering app. However i encountered quite a problem in the process. When I clicked viewport render, the imported
looks like you may have “z” fighting where two planes occupy the same space?
Also make sure that backface of the geometry is not facing the camera.
I don’t know anything about Vray, but with many renderers it is safest to explode imported images or import them originally as textures to get the most consistent behaviour.
Upload your file I will investigate it.