After a macOS update you may find that the USB keyboard commands on Nucleus and Matrix no longer function.
The solution is to reset your keyboard preferences via the Mac Terminal app.
First, enter the following command in Terminal:
sudo defaults delete /Library/Preferences/com.apple.keyboardtype
Then, disconnect and reconnect the USB cable – this will prompt the keyboard identification wizard to open.
Select the keyBID (keyboard ID) switch on the SSL (by default, it is the top right-hand corner switch on the Nucleus) – this should close the wizard, and correct operation should resume.
If that does not work, make sure you are running the latest console software version. As of November 2021 that is Nucleus V2.0/2 and Matrix V3.0/5.
If you cannot find the keyBID switch on your console, search for the phrase 'Keyboard ID' in the manual.