I have already read the stickied post and checked, that the process privileges are fine, in fact I even disabled UAC. Still not able to even show the FPS counter in the Il2 Cliffs of Dover, which uses dx11.2 on my fresh installed windows 8.1 64 bit, Radeon R9 270 OC. Steam community features are also turned off.
Radeonpro works fine with other games and 3d-applications, including another DX11 game.
Maybe it has something to do with the fact, that the game apparently uses some native windows classes for GUI (at least it looks like it. The mouse is the default-windows mouse, and there are windows-styled context-menus).