I have had this happen 3 times now. Some background is I had some ghost devices I could not get rid of. I hadn't done much automation yet inside Hubitat so I decided to rebuild from my system from scratch. Removed everything and did full Z-Wave reset and reset on Hub. I then added most of my devices back in (around 40). I first noticed this happen a week or so later when trying to add in a device and it would not pair. I checked and found the list blank. I still see all the devices under the device section and automation still work. So shutting down the hub and powering off for a few minutes does fix this. However this is the third time it has happen now in a couple weeks. Restarting does not fix the issue. Only full shutdown and pulling power. Should I try doing a Z-wave repair.
Z-Wave repair won't correct this. Can you post your Zwave Details, sounds like there still may be a device issue.
Tagging @support_team.
I’ve seen one other report of this issue. And I think in that case, a Soft Reset followed by database restore fixed it.
This is not normal, please send me a PM along with your hub's MAC address, I would like to further investigate.
The one time I've had this happen to me was immediately after the 7.17 upgrade, but IIRC there have been instances where a device caused a similar issue; in my instance a power down restart corrected it. Your devices look good, so I'm going to bow out and let HE Master Jedi @bobbyD do his magic. 
Still loosing the Z-wave details. What are the steps for a soft reset with database restore. Do you use the latest database backup?
https://docs.hubitat.com/index.php?title=Soft_Reset
I usually download a current backup right before doing this.
What @thebearmay said. Then use the one you downloaded to your pc to restore. That will ensure the database is clean.
Did the restore last night and shutdown restart. Device came back, but when I checked again this morning everything gone. 
