Siri/Home app won't set thermostat to certain temperatures
I have a HomeKit enabled Honeywell Home Pro Series thermostat. I have no issues adjusting the temperature using the thermostat itself or its native Resideo app. The problem is when I ask Siri to set the temperature to 73 degrees F. Or if I open the Home app and try to adjust the temperature manually. The app lets me set the temperature to 73 degrees, but after a second, it will snap back to 74 degrees. This is for AC. I've tried a few other temperatures and Home/Siri seems to have no problem adjusting to 72 or 75, etc.
I know Siri is communicating with the thermostat because even though the temperature never gets adjusted, the thermostat changes from "Following schedule" to "Hold until 1PM" which it does if you ever adjust the thermostat from its normal schedule. I have three thermostats (1 per floor) and Home/Siri does the same for all three. A long time ago I thought I read of this problem and it had to do with the way Home calculates temperature between Fahrenheit and Celsius and some rounding. I use Fahrenheit. Could this be true?