You may be running in the deadband issue with the stock DTH. The way it work is that is maintains a minimum gap between the heating and cooling setpoint. This if fixed in the stock DTH irrespective of the thermostat model.
Also keep in mind the some thermostats like the GC-TBZ48 allow you to configure this deadband. This feature is a type of protection to prevent hunting/rapid mode changes which can hurt the compressor.
If you’re using the Enhanced Z-Wave Thermostat DTH, it allows to configure the deadband for your thermostat model and then also synchronize that with SmartThings.
Also, keep in mind that mesh issues may cause some packets to be lost, so if you send two commands in quick succession one of them may be lost which is what you’re experiencing (which can start at anytime due to the nature of th mesh). There are a couple of ways to mitigate this.
- Some thermostats support Listening mode, i.e. they are on all the time and listening for (and repeating) messages, rather than sleeping (FLiRS). For this to work the thermostat should not be battery and should have been paired with the C-Wire connected. If you aren’t sure you can look at the raw description of your thermostat in the IDE and post it here and it’ll tell you how it was paired. If it’s not in listening mode it usually helps to exclude and re pair in listening mode with the C-Wire attached.
- Try adding some repeaters close by which buffer messages. These again help to avoid packet loss and can improve the quality of the mesh.