Well, I went through the exact same thing on an out-of-the-box C-7 yesterday. Turned in a support ticket but only got the autoresponder that has happened on all my tickets on my C-5 since May. Anyway, here is a brief summary that I posted late yesterday afternoon about the steps that I took to finally resolve it (I think):
https://community.hubitat.com/t/unknown-z-wave-devices/48424/14
