Have been following this thread with interest. My ‘hunch,’ like Megan’s, is data corruption.
Three of my devices have shown errant reports–false positives in my case–over the course of three years of continuous operation. All are ZWave. All were used as inputs to SHM. Is it the ZWave stack in the hub? Is it something in the data transport from hub to cloud? Is it something clobbering the device data after it arrives in the cloud? I have no way to know and suspect there have been other issues in my two ST systems that I just never noticed.
My latest issue–and how I ‘fixed’ it remotely-- is described here (see Is there a way to recheck a door sensor?) if you’re intersted…