Yup, I have 16 of them paired.
In general, if you try to pair and nothing shows up in the zwave details page, either wait 5 minutes or reboot the hub. Odds are after you reboot you will see stranded (not "ghost" - there is a difference) device(s) in the details page with a "discover" button. That is true of any device pairing that doesn't complete successfully - not just these Zooz devices.
My recommendation is always, if the pairing times out even when pairing close to the hub - reboot the hub and see if it really did start the pairing process, but never finished. I've seen that at least 30 times now... As I know how to work around it, I've given up trying to understand why it happens.
I had to do that multiple times while I was pairing those 16 devices as the pairing process didn't always complete correctly - for whatever reason.
After pressing discover / waking the device up a time or two the device would be added correctly (as seen in the logs). At first you will get tons of "zwave busy" messages in the log, but usually after just a time or two doing discover/waking device up it will finish.
Also, I would recommend pairing these devices close to the hub, not far away (like I usually do). I had issues when pairing these via NWI.