Enable Performance Recording On/Off    ⌃P

The “record enable” button for the loops. I would have thought a simple ‘R’ button like all the other record enable buttons.

Record a Live Loops performance — Apple Support

You can record a Live Loops performance to the Tracks area. After you are done recording your Live Loops performance, you can play it back in the Tracks area, edit the regions, and finalize the mix.