First of all I created a sphere with a default corona mtl and put a corona light in side of it. Render should be completely black, but some fireflies appear on the surface. If I turn on reflections a strong outline appears:
The problem gets much worse if you add a bump map. Here I disabled diffuse and added a simple noise as a bump, but the bug is visible with any other procedural map, texture or normal map. No other material properties were changed.
Here is the worst case example with brick texture, low filtering blur and bump value at 2. Underneath is just a plane with checker map. It almost looks like the texture somehow got into an opacity slot.
I tested with max 2014 and 2016 and earlier versions of Corona but the bug is still the and the effect is even stronger. However a6 renders normally, so maybe this has something to do with ggx implementation since v1.0
