No disk with serial '9XG9N7Q6' found -

I have about 20 machine nodes for this lab I’m working in. They are all Quanta machines, which is not a very solid platform, but it is what it is. I’m getting a LOT of these errors lately:

curtin: Installation started. (18.2-10-g7afd77fa-0ubuntu1~18.04.1)
no disk with serial '9XG9N7Q6' found
curtin: Installation failed with exception: Unexpected error while running command.
Command: ['curtin', 'block-meta', 'custom']
Exit code: 3
Reason: -
Stdout: no disk with serial '9XG9N7Q6' found
Stderr: ''

The only way to recover from this is to re-commission the machine. Will someone please shed some light on this issue for me? Note that the serial for the disk is always “9XG9N7Q6” for any machine on which this error occurs.