Yeah that usually happens if there is more than 1 neighbors showing. It seems to be a bug in the Si Labs provided z-wave gateway being used on the hub. Only other option is to get a USB stick and remove then with the Si Labs developer software. There is a guide on the forums How To: Remove Ghosts using hub tools or a UZB Stick
I just went through this on a hub for someone. Had a dozen or so dead nodes with the Discover button. Once I got the software setup I had all the ghosts removed in 15 minutes (mostly waiting after clicking the remove button).
