Every time i start games that go full screen, they get minimized. Only exception is the first start of a game. After i quit it, only a log off log in of my user get it to work once more.
It seems to be related to display scaling. It works if it is set to 100%. Mine is set to 150%.
If set to 150% a nice tool called focus.exe (https://www.happydroid.com/focus) logs who is stealing the focus, my log is this:
3004:C:\Spiele\Tomb Raider 2\tomb2.exe | Sun 26 February 15:43:30
3680:C:\Program Files\AMD\CNext\CNext\RadeonSoftware.exe | Sun 26 February 15:43:31
8032:C:\Users\Sten\Desktop\focus.exe | Sun 26 February 15:43:35
So it's definitively a setting or a driver issue