I am still seeing a pairing date of 5/1/2021 for that thermostat on your account. Now that the thermostat is powered, to troubleshoot the communication malfunction it needs to be deleted and relearned.
When powered by AC, your Tstat can have its display on at all times. This is a setting.
In Alarm.com on the Thermostats card, click the arrow.
Click Advanced Configuration.
Click User.
In Display ON, select Enabled or Disabled as desired.