You need to poll the T6 periodically, see this thread
I have also recently noticed an issue with the thermostat display, where instead of displaying temperature in the big font, sometime it displays the setpoint. For example, it may show 60 (as temp) and 60 as the setpoint. When it really should be showing 61 as the temp. After some period of time it reverts. So I suspect that sometime when setpoints come from zwave the display chooses to show the setpoint rather than the temperature until the temperature changes. I spent a couple of days on this and reached that conclusion. The good news is that the data in HA always seems to be correct - or at least once you poll it.