I also experienced synchronization problems with GPS 72H connected via direct USB (Garmin Driver 2.3) due to 12V power supply outages (faulty contact inside cigarette lighter plug).
I did not want to fiddle too much with the software
or computer setup underway, so I usually did not try to manipulate to resynchronize. Just powering down and restarting - PC and OCPN first, GPS second, got me back to shape in 2 minutes every time.
It was a nuisance, but not too serious. Worse was the 70MB of error messages in the log, and the trouble to stop this error stream...