I had this happen on my PC and it was being caused by the presence of a virtual network adapter. Uninstalled it and the “Things” scan completed in a reasonable amount of time, like a couple of minutes.
In my case it was NPCAP Loopback Adapter. I use it for Wireshark and a few other utilities.
The things scan will eventually finish, but I did turn off the automatic scans and just do them manually as needed. In my case it runs about 30 mins each time.
It seems like the virtual loopback adapter is presenting a device state that the scan is having a hard time dealing with. I would guess that maybe some sort of timeout is occurring, or many levels of recursion in a search algorithm?
This is probably fixable by just having the scan ignore virtual network adapters.