Same for me. I’ve had to turn off “Device Delayed” and “Device Not Reporting” notifications in the Device Monitor settings or else I’m being inundated with notifications. I now am relying exclusively on using ONLINE/OFFLINE status. I believe this issue has come up due to the change to the latest firmware release and how ST is now determining “Device Delayed” and “Device Not Reporting” states.
Device offline monitoring service transition
Upon the launch of hub firmware 0.32.x (target fall 2020), the current cloud-based system for monitoring the status of Hub-connected devices will be replaced with a new service that runs locally on SmartThings hubs.
In my case, both the Device Monitor and the IDE are now reporting 'Devices Reporting (hours old) for the majority of my devices as many hours old. I’ve checked and most (not all) Z-Wave devices are not properly reporting (i.e., many hours old) but even some Zigbee devices are also not reporting correctly. It appears to me to be a brand-specific issue. For instance, all of my Jasco/GE Z-Wave devices and (Zigbee) Cree Bulbs are incorrectly reporting. This is not an inclusive analysis, but it’s a start.