Unfortunately Homey (still) does not provide for a “consider device to be offline after x hours” detection, unlike zigbee2mqtt f.i.
In the almost 5 years of using Homey, I’ve never seen any news on this, presumably Athom won’t “admit” the fact sensors can stop responding for whatever reason.
So, it’s best to create checks yourself.
You can use a timer, like
If..
device Z value X has changed
Then..
start or replace timer Y, duration 4h
(4h just being an example timeframe)
If..
timer Y has finished
Then..
send warning: device Z value X didn’t change for 4h straight
Or, a bit more sophisticated, use a cool script by @sharkys to catch them all:
