It prints his jobs, but auto deletes are soon as the Xerox gets them.
If it deletes it, it doesn't get printed, please explain what you meant here.
They show the job as "unknown" on the Xerox, which is his print jobs, but it auto deletes it.
Unknown happens due to the port, change it from RAW to LPR
And even a deleted job should have a reason associated, just go to Job Status > Completed Jobs and select it to get the status.
And since it is all down to the one user, you know it isn't the printer, so the driver, or the user account if accounting is in use, will be the issue