When I turn off my monitor (or when it goes into power-save), and turn it on again, the maximum resolution is reset to 1368x768. This already messes up any screen layout at HD, but it is extremely bad for a UHD (4k) screen.
Even worse, I have to reboot to get the original resolutions back. This is a severe issue.
It happened with a recent update (maybe to 4.15.1), and it occurs on two different systems (both with amdgpu). Seems as if I have to roll back.