Somewhat unrelated, but NVidia users have the same problem ( Source ).
The temporary solution for NVidia is switching to “auto”, wait 5 seconds, then back to “max performance” in the NVidia control panel under “powermixer”. every restart. Its pretty much confirmed that the flicker bug on pascal (10xx/20xx) cards is related to the GPU switching power states.
Maybe there is something similar going on with AMD and its actually a kernel problem?