this started a few days back. we'd been using print center just fine for a number of users, when suddenly every pdf/docx/etc. that was uploaded would process (say "uploading - 100% done) and finish with "one or more errors occurred." next to the title. nothing except the printing time elapsed shows on the print center page. in the alerts it's the old "unable to print zero length print job".
running print center 1.7, pharos 9, server 2008R2.
It's possible that your Mobile Print has been set to disabled (internally). Try stopping and restarting the Mobile Print Workflow Service then wait a few moments before trying to upload another job. If this still doesn't help, then try resetting IIS (then waiting a few moments) then trying another upload. If you still see the problem, I would suggest opening a ticket with Support.
Hope this helps.