Tuya/Hama zigbee thermostats not adjusting to temperature changes

I have these: https://www.computeruniverse.net/en/p/90814471
They’re identical with the Tuya models. They work in the tuya integration.
However, they seem to fully ignore the set temperature. If it’s set to 21°, it can be sitting at 19.5° (measured by the thermostat itself, mind you) for hours and never attempt to correct it.
HA reports the status as “off” all the time, too.
The thermostat DOES heat up in the morning, when I programmed a temperature rise for the day… it just seems to have a really large margin during which it decides not to do anything. Is there any way to adjust/force this?

I have the same issue!