Hi,
I don't know if it is a bug or I'm doing something wrong.
So, I have a refractive object (glass, ior 1.5 ) and a Label with a text. The label is in its own material (Diffuse + Opacity). I stack them the C4D way on the object. In the render result, it is clearly visible, that the IOR changes. I would expect, that the IOR of the underlying glass is used when I stack a label with no refractive over it.
If you compare two renderings, only the glass and one time with the label so see the difference.
Thanks,
Helge