Screen shot not working on M1 Mac mini and Big Sur.
When I Shift, Command, 3 or 4 it just clicks but doesn’t take a screenshot or show me the marker to select selection/ portion of the screen.
Question marked as
Startup in Safe Mode followed by a normal restart and test.
https://support.apple.com/en-us/HT201262
Double check to see where your Screenshot are being saved.
https://support.apple.com/en-us/HT201361
Check your shortcuts. Apple > System Preferences > Keyboard > Shortcuts