Overview
Full ScreenSamsung 55Q8CGeForce GTX 1080 Ti4K3840x2160PC-Version
PROBLEM
on a PC with a 4K display the game settings might not offer a resolution higher than 1920×1080
(Windows Scaling already down to 100%)
fullscreen not working
SOLUTION
get the game in full screen by changing the properties of the GPU from 3840×2160 @60Hz to 3840×2160 @59Hz
now the gamesettings offer resolution 3840×2160 (4K)
change the settings to 4K
after doing so you can change the properties of the GPU back to 3840×2160 @60Hz