Not a fix, but a possible work-around:
I think if you downgrade the hub itself to 2.3.6 firmware it may work. I am guessing something with the update button got botched up with the new UI. On 2.3.7 that button was missing and they added it back in 2.3.8, possibly is broken.
Use this URL to download the last 2.3.6 release:
http://HUB.IP/hub/advanced/downloadPlatform/236
It will spin for a while just let it go.
Then use the diagnostic tool and "Restore Previous Version" button.
-- Hubitat Diagnostic Tool | Hubitat Documentation
Once Zwave FW is updated you can update back to 2.3.8
