For a temporary fix, I understand you can turn off the house batteries for about 5 minutes and that will reset the thermostat. I've also read you can pull the fuse in the thermostat and leave it unplugged for 5 minutes to do the same thing.
If you search the internet for RV comfort zc thermostat, you'll probably find several post about this procedure and what causes the problem. Several sites says it's an electronic interference that can be caused by fluorescent light ballast, phone chargers, vent fans, etc. They say to put in a choke filter.