Command-C stops working

budoman wrote:

How can I determine why Command-C stops working?

So from time to time (frequently), I'll be working in Photoshop, Illustrator, or Apple Mail and for no apparent reason the Command-C shortcut stops being recognized. I'll copy something then go to paste only to discover that it is pasting the previous item from the clipboard. Then I notice that invoking Command-C isn't copying anymore. How can I troubleshoot/prevent/fix this issue. Happening in Catalina.

Try rebooting and test.

Try a Safeboot to clear system cache files, reboot as normal and test

if no insight or resolve, test in a new user account:  https://support.apple.com/guide/mac-help/set-up-other-users-on-your-mac-mtusr001/mac and compare your results.

AFAIK the Command + c is a native Keyboard shortcut in OS X Tiger10.4 and every newer version of OSX and macOS. This unless one has remanded this shortcut to perform some other function.