HA and ISY- Spurious action

I am new to HA, but fairly tech savy (old time software developer). I have had HA running for a couple of weeks on a Pi4, and all seems well - not much happening with it yet. The other day I added the UDI/ISY integration, so I could get access to my ISY/Insteon network from HA. This seemed to go ok, and I can see all the various devices. The problem is, when I open my back door, “something” is sending a signal to a relay to turn on. I have NO scenes or programs in the UDI/ISY environment that in any way connect these 2 devices, and in fact, nothing at all that responds to that sensor (it is not even IN the UDI/ISY - only on HA). In the HA logbooks, I see that the relay is:
“turned on triggered by service Switch: Turn on
4:05:35 PM - 15 minutes ago - Supervisor”

How can I find out what caused the Supervsior to do this? I have NO automations set up, and only a couple of Node Red scripts, but they do not touch this device.