SSS materials seem to ignore when you use Render Mask Selected. SSS materials seem to render no matter what. Not sure if this is a known issue or not, but wanted to throw it out there.
-Joel
I have tried rendering a scene with some Fast SSS materials, but it seems that the Render Mask(Selected) isworking fine. Could you tell us which version of V-Ray are you using and also is it possible to share with us a test scene, so we could further investigate this.
I hit it with 3.60.03 and it seems to be working with a simpler scene, both in bucket and progressive. Perhaps something was choking up on my large scene that causes it to happen? It is something I cannot send unfortunately, but will see if I can reproduce in another way. It is a complex surface with SSS and VrayDisplacement, simpler recreations all work fine in new build. Perhaps it was fixed. If it ever reappears, I will post a file.
Thanks for the feedback. I will try to do some more tests, but it would be best If you find a way to reproduce it on another scene and send it to us.