So I've been trying to set this up but I ran into two issues. One it doesn't work at all with some imported CAD models(which I cant share), but CAD models are often odd so it's something I've got to live with.
The second one is a phantom disc appearing seemingly random. I recreated the problem with a sphere with some holes punched in it and a cube catching reflections. As I change the difuse color closer to white at some point a disc occluding the reflections appears.
Corona 6RC2
R18