If you clone a Zvol to a different dataset within the same pool, it “works” and shows up in the GUI just fine and also in zfs list -t volume
But first it doesn’t seem possible to create a clone inside a DIFFERENT dataset in the same pool, even though it appears to work. Am I wrong?
So if you delete the offending clone, your ZVol listing in Disk>Edit Device will no longer spin.
I’ve just reported the bug to IX Systems as [NAS-129021] - iXsystems TrueNAS Jira