Since I upgraded my OS on my MKIII to v22.1, I'm having the same issue.
Worked fine before the upgrade of the software.
The only thing odd or different about the upgrade was that I got an error message twice when I tried to load the software upgrade.....it took the third time around.
I haven't tried pulling power from the nav system or disconnecting the battery yet to see if it will reset.
Should I try that first?
I'd rather go back to the old software than deal with the constant resetting of the monitor....is that an option? If so, where would I find the software for the older versions of the firmware?