thermostat not clicking

We have three zones on our furnace, each with an thermostat, all connected to a Frontpoint security system. One of the thermostats (in the zone where everyone is working from home!) is not adjusting the temperature. Whether manually or via the app, thermostat will not click when we adjust the temp to a higher degree.
What we’ve tried:
-changed batteries
-cleaned the connection between thermostat and wall panel (with air spray)
-turned Mode on, off, auto
-turned schedule on, off
-changed high and low setpoints
-changed setting to heat, auto, on
-adjusted the temp manually - when we do this, the thermostat “heat” symbol flashes a couple of times, then the thermostat temp jumps back to current temp, and the flashing stops, nothing happens.
We can’t hear any clicks in the thermostat.
Please advise.
Thank you!

Have you tried removing the TSTAT from the Z-Wave network and re-adding it?

Has this problem occurred before, or is it new?