This is likely experiencing signaling issues due to the ongoing operations alert here:
There is an issue affecting some Verizon LTE modules causing failures at the carrier level. Alarm.com and Verizon are working on this now.
Enabling dual path by connecting the panel to wifi is recommended.
I would try powering down the system for 2 minutes, then power back up, wait a few minutes and run a cell test. Any luck? If not you are likely experiencing this carrier issue. It should be resolved without the need for additional troubleshooting soon.
Adding wifi will allow the system to communicate via broadband.