LM21 Steam: New game play window won’t open

Steam w/Proton works for 1st game installed. On 2nd game, however, game installed and appears to be running (see left side menu) but there is no window opening to play the game. I am a beginner and need step by step help.

I found this fix on YouTube but don’t know how to use it on Linux: https://youtu.be/1J35Xesggpo