Had a rule running for years whereby a switch is turned off with a load of others things. Randomly the switch has stopped turning off however still responds to a manual turn off. Turns on perfectly well. Anyone else had this before?
Probably, but it almost always comes down to some problem with the app or device. Without more information, it's hard to know where to start troubleshooting.
Since you mentioned a rule and seem to believe the issue is there and not with the device itself, the best place to start would be to look at this doc and pay particular attention to the sections on "Enable Logging" and "Check Logs" under "App Troubleshooting" (but the whole thing might be useful for more):
Can you still control the lights from the device page? First thing I'd try is going into the rule and saving it. What are the triggers and conditions to turn it off? Is it the only one not working ?
yeah its odd, i'm still able to turn the device on and office from the device page. The trigger triggers a group of devices to go off which this one is in and all the others do go off. This one used to but unsure whats changed