My Book Duo 20T causing kernel panic at shutdown with Big Sur

I have isolated a kernel panic issue occurring at shutdown in Big Sur to the Duo 20T I am using as a backup. It backs up fine, but causes the panic. Any ideas?
Thanks

If the drive simply boots, there is not an issue, but when the backup is written, it causes a kernel panic at shutdown. I have switched to manual backups so I know when to expect it.