Reset All Preferences to Default removes essential keyboard shortcuts; fixed on restart
To reproduce, open MuseScore's Preferences and click the "Reset All Preferences to Default" button. Result: essential keyboard shortcuts are removed. By "essential shortcuts," I mean things like Close, Save, and Undo. I noticed this once before but couldn't figure out what has caused it: https://musescore.org/en/node/50486#comment-238896 Now I figured it out… and now I think I have to do another factory reset, because I'm not sure of all the shortcuts that are missing.