Yeah that sounds strange - maybe your air-gapped switch only cuts power to the load?? --> this is a silly thought apologies!!
I think @thebearmay's idea is worth a try.
I might click on the Pc Controller device, then in the bottom right frame click on "update" button to refresh the controller with the Hub info (Gateway).
Another thought would be to exclude the stick and reinclude it again for giggles. You do this by starting the "remove" process from the HE device page then in the PCS clicking on "Select Learn Mode" / NWE...
Yet another thought is to reboot your hub to clear out any cobwebs and maybe try another removal from there.. My usual would be to suggest the old power pull / wait but it seems like this might actually not be necessary according to staff member Bryan the resident Z-Wave expert and all around good doobie..
