Zilla Thermostat

Curious if anyone has issues with Zilla Thermostat?
Have two zoo-med digital thermometers, one under warm hide and one in the warm ambient zone. Thermostat is under warm hide. Thermometer in the hide fluctuates in readings without changing thermostat.

The same thing happens with my zoo med digi and i hsve 2 differrnt thermo probes under the warm hide

They have pretty bad reviews, I just stayed away. A lot of the reviews say that they either don't work for crap or break after like 3 months.