I’ve been having an issue where a couple of my Zigbee devices will stop communicating back to the hub. I didn’t see a way to monitor for this event using the SmartThings custom trigger or Rule Machine and the only way I could find when devices were “offline” was to check the recent history and look for any status updates. So I wrote a little app that checks to make sure devices have reported a status update. You can choose to do temperature (my preferred method and probably the most reliable) or a contact status and then a time interval (24, 48, 72, or 96 hours). If the app doesn’t see a temperature or contact update within the interval chosen, it can send a push or text notification.
Not sure if this is helpful for anyone or not, but figured I’d post it just in case.
I can easily add other device types if desired.