Make sure direct X is updated and you have your latest GPU drivers?
If your on Linux that's a bit tougher but probably something like that with drivers?
After that try uninstalling it and reinstall the game?
Edit: You could also try rebooting? see if that solves the issue, make sure other programs are not running in the background like screen recording software or anything that might display over other apps. Might also try disabling antivirus software if it's blocking something? (Temporarily just to check if it is.)