Unlikely that you could tweak your UI brightness in such a way that it kills both grey tones at the same time, so this is a real issue of sorts. do you see any propagation status updated on teh info plaette? Please check that. If there is propagation, yet it does not show up in the viewer, it may be an issue with your footage. And no, you shouldn't use masks and RB at the same time. It may throw off RB completely. You would have to pre-compose or pre-render the RB layer and work based on that.