By my experience, multi-touch crashes on a per-app basis. I could quit the app and relaunch it, and gestures would be back.
Apparently, sleeping the display and then waking up the system again will bring back crippled gesture. You can click button to do that, or just close the lid, or use terminal:pmset displaysleepnow; sleep 5; caffeinate -u -t 1
After one second of black screen, gestures are back.
[Worked for me, although I have a screen sleep corner, so easy enough. I hope Apple fixes this, it’s become a little too routine.]