If this problem does occur could you add here dump from opera:gpu page?
So far we seem to have seen that disabling opera://flags/#enable-gpu-rasterization seem to be enough to get this working without disabling whole Hardware Acceleration. Also issue seems to affect only certain AMD card configurations. As we can't reproduce locally it's hard for us to narrow it down.
Also if problem does occur for you could you check if it appears also on today released beta build (48.0.2685.7)?