I have Vivint CT200 thermostats that work just ducky under the old app. They migrated to the new app as expected and I can read the current temp.
However, if I try to adjust the temp or the mode, it doesn’t change the thermostat.
Try to exclude and re-pair your thermostat. You may try to reset your thermostat with reset button as explained on this topic also which could repair a broken connection: [RELEASE] Enhanced Z-Wave Thermostat Device Handler with Z-Wave Plus
Thanks. I’ll give it a whack and report back.