Not 100% sure this is the fix since I recently found this myself but so far it works.   If you use windows 10: Go to the emby theatre.exe (start -> run -> %AppData% -> emby-theater -> system -> Emby.Theater.exe) and go to properties. Go to compatibility tab and then at the bottom turn on "disable full screen optimizations"   Unfortunately microsoft always adds nice things to windows, that turn out to be crappy functionality 60% of the time. I am still looking into turning t