Ok. For the good of the broader Hubitat community, I am going to put my ignorance on full display, with the hope that it may assist someone else in the future
. As you read this, bear in mind, while today I'm a Z-Wave amateur, when I first started a few years ago, I REALLY didn't know what I was doing.
As you pointed out, I had four ghost nodes on my network. One "GENERIC_TYPE SWITCH_BINARY" and three "SPECIFIC_TYPE PC_CONTROLLER". I could not figure out how to get one particular "SPECIFIC_TYPE PC_CONTROLLER" removed from my network. The others removed exactly as described on the Ghost Node Removal instructions.
After seeing your comment, I popped the Z-Wave stick back into my computer to do some more investigating. When I selected that device within the ZWaveControllerUI app and clicked "Is Failed", it would not go to "Failed" status, therefore I could not remove. I looked closer.
It didn't fail because it was still communicating on my Z-Wave network.
Given that I have had to manually remove a Z-Wave stick from my network several times before, I assumed that is what this device represented.
I found the "fingerprint mfr: "008B", prod:"5441"". After some googling, I found this:
XL1050 – Z-Wave Alliance Product Catalog
At some point, years ago (when I was much dumber), I added my thermostat to my network (clearly, I had forgotten this). At the time, I didn't understand that this was a controller or that it joined this Hubitat Z-Wave network as a secondary controller. I was able to remove it via the normal exclusion process.
Now we know why, of the multiple Z-Wave networks in my home, only this one was affected. There is a part I still don't understand. Why now and why only physical switches? Maybe we will never know. Maybe it doesn't really matter. If we could get to the bottom of it, it might assist in keeping me or someone else from making another bonehead move like this in the future.