Kaldek

OK the logic was flawed. I kept going and found the actual root cause.

I have some file backup trimming scripts that were still running on non-existent directories with poor logic. The directories didn't exist, and the file deletion runs in whatever directory cron is running from.
You can see where this is going.

Support had to do a manual key replacement to fix this issue.
 
I literally just listened to the unRAID podcast where the support guys were saying license key management was a major headache.   Guess there's still a lot of work to do at the back end.

I bit the bullet and did it.  I confirmed that keeping Pool Slot assignments also keeps ZFS pools.