Ok, now I'm afraid to turn off my computer or even stop any Debian template based VM's...
Here is what happened.
I was going to do a general update on Dom0 and my Debian-10 and Fedora-32 templates.
As is my habit, I deleted the older clones of those template VM's and was creating new clones with qvm-clone from a Dom0 command window.
While attempting to create a new clone of the Debian-10 template, it halted with an error:
file pool cannot export dirty volumes.
Searching for that issue suggested I start the template VM and exit it cleanly...although I don't have a recollection of a "dirty" exit (crash, kill etc...).
I went to start the template with qvm-start and it won't, giving the error:
file pool cannot start a VM with an exported volume.
How in the world do I recover from this?