"Error: Could not locate a zvol for"

I’m occasionally getting an “Error: Could not locate a zvol for lxdpool/containers/(…)” when trying to start the container, which breaks my backup script that stops containers and copies them into the backup location. After the second try, it usually works just fine. Any idea what it could be?

My LXD version is 5.19.

Also, I’m running LXD on the Ubuntu 22.04. I was going to migrate to Incus eventually, but I would like to understand this situation first, to not lose any data if there is some underlying bigger problem in my setup.