I would use this app to monitor for inactive device: [RELEASE] Device Activity Check - Get notifications for "inactive" devices
All my drivers are setup so the lastActivity date/time that app uses should ONLY get updated if the device sends a report to the hub, and it will update if you send a refresh to the device. Due to this they work great with that app. Have not implemented the "healthStatus" attribute yet but may consider adding that eventually.
I think the self-test feature is enabled by default so yours was possibly doing that all along, unless you had turns the setting off by mistake. Its good because it keeps the valve loosened up as well, so when you really need it to work it does not get stuck.