Just been trying to sot this out again today…it’s annoying.
The offending shortcuts (Control, 2,3,4) have the words “System reserved” next to them in the Command Editor.
I did have to disable a system shortcut in Keyboard OS preferences to get control 1 to work (Mission Control switch to desktop 1 is also Control 1).
I’ve been on to Apple and trashed prefs and trashed system refs but still no cigar.
Bizarrely if I log in as another “guest” user and launch FCP, those shortcuts are not greyed out in the command editor and work.
Somebody clever out there may know????
Have a good weekend all