That’s pretty cold
I've seen the zen do this on an Xfinity system and power cycle cleared it, however it did come back a month or so later at which point the thermostat was just swapped for a new one.
Apparently, it has not taken as long for the problem to pop up again. This morning, it did not change on schedule. I have a rule that is supposed to run and check periodically and set it if that happens, but that also did not take place. I again rebooted the thermostat and ran my rule again. It finally took.
Enough is enough. I just ordered a Centralite Pearl thermostat. I'm not sure if it will be any better, but the current situation is not satisfactory.
The new Centralite Pearl thermostat arrived a couple of days ago. I did not install it immediately as I wanted to see if the Zen was going to work properly. Today, it appears to have totally failed. I installed the Pearl this afternoon. I did not immediately see the Zigbee connection information, so I thought I had goofed. I looked a little closer and saw how to initiate the network join. Then it was simple to finish getting it connected.
We'll see how well the Pearl behaves.