I believe support team are aware of this issue, and have been investigating it. I am not sure when the fix will happen, many are recommending extending your backup interval to minimize the issue as well as taking a manual backup to ensure you have a clean and current backup.
One approach to minimize disruptions until a fix is released:
Turn off scheduled backups
Manually backup when you make significant changes on your hub
That way you're watching things when the backup completes and can respond appropriately if Z-Wave devices are affected, rather than having things down for a while if the backup runs unattended.
Does require you remember to do the backup after making significant changes, which I know from personal experience can be a challenge.
I think you should keep it unplugged for at least a minute.
Also, you mentioned "reboot"...did you reboot after you plugged back in?
Usually a shutdown/power cycle with a minute break brings it back.
Also, it should be made clear this problem is associated with cloud backups, which could affect the radios.
Not local backups, which don't do radios.
So, what I've done lately, per @JasonJoel 's advice, is to keep my daily local backup, since I'm always tinkering with rules, but stretch out the interval for cloud backups to two weeks, OR, whenever a device is added.
I'm past the stage of adding a new device every day, for now.
Based on some statements from folks here smarter than me I think it doesn't really require a full minute - I do usally tell people to "wait a minute" just to make sure they don't immediately plug it back in.
Just to be clear, you can do a manual Cloud Backup, which will include radios.
I'd recommend just rolling back to the previous version and waiting until the problem is fixed before rolling forward. I rolled back to version 2.3.7.140 and the cloud backups are running normally again.
This is a very YMMV issue - affecting some people/some hubs, so really hard to tell what may help in any individual situation. That intermittentness of the issue is likely what is making this a difficult nut for HE to crack...glad I'm not trying to figure it out (and you all should be glad I'm not involved as well).
Is there any sort of resolution on this? I am on 2.3.8.125 and shutdown and reboot solve the issue for a bit, but within 24 hours the hub becomes unusable (I'm primarily z-wave).
I have turned off any auto backups, but it's still happening.