I've noticed that there are problems on my system (Win8.1, nVidia GTX660) and legacy fullscreen applications (games).
This only affects some applications. It runs, then loses focus. When I try to activate the main window it immediately loses focus (again).
The workaround for me was to kill creative cloud.exe. I originally wanted to submit a bug report but got here
One application that behaves like this is Deus Ex: Invisible War.
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