Keyboard shortcut for "Select All Similar Object" quits working repeatedly

For the second time now, my custom keyboard shortcut for "Select all similar objects" stopped working. I used two different combos; Cmnd+Alt+A and Cmnd+Ctrl+A. I defined the 1st shortcut several weeks back and it worked great until I believe last week when it stopped responding. I tried to replace the shortcut with another combo and it didn't work as well. So, I turned to your help forums, where somewhere mentioned that a reset to default preferences with a certain code (with the Mac's terminal) should fix the problem. I did it, then reconfigured the shortcut with the 2nd combo and got back to using the app.
Now it's happened again - the "Select all similar objects" function in unresponsive using keyboard shortcuts. I now tried only to uninstall and reinstall MuseScore - that still doesn't work. All other self-configured functions work fine.

I'd really appreciate a response or an update on this matter, I use this function A LOT :(

All the best,
Meit
meit.botton@gmail.com