I was really hoping the issue I encountered in VRED 2014 regarding a ShadowPlane's edges not rendering transparent would have been fixed for 2015 SP1, but that doesn't seem to be the case.
It seems that the root cause is incandescence being turned on for a material. The issue persists, even when you turn it off or delete the material. There might be a connection with creating standard lights, but I'm not certain. This shows in Raytracing- it looks like the Shadow plane is a light black square, though the actual shadow area is correctly darker.
The working file seems forever corrupted after this occurs.
