Stuck on centering can be caused by a lot of things, from a dirty camera lens, or your Wifi provider dropping a signal while data was being transferred back and forth, to a loose connection somewhere. I think the most common cause is the Wifi signal getting dropped for a fraction of a second somewhere along the route that the data travels. The last command it was working on gets hung up. (Although dirty lenses or too much glare rank a close second.)
Try resetting the machine: Turn off the machine, your router, and the computer for a minute - then turn them back on and let them finish rebooting before turning the Glowforge back on. Let it finish the startup calibration before sending any commands or trying to run a job.
For me, waiting a little while and rebooting everything has always worked to restore operation, however if the problem is with your ISP, you might have to try it a couple of times. If that doesn’t work, then you’ll want to open a ticket.
The Troubleshooting section has a little more detail on steps to try to fix Wifi issues when they happen.
Troubleshooting - Stuck Calibrating
Troubleshooting - WiFi issues