If you are printing (particularly when printing from Google drive/documents) make sure the paper size is set to LETTER and not A4.


If the release page says unable to release then there is a physical issue with the printer (needs toner, jammed, etc).  This error should be visible on the home screen.

If the job disappears from release screen and machine doesn't start printing, that usually means the system doesn't have the requested paper loaded.
To check what is holding things up:
Home screen, Jobs widget, select job with colored icon (grey is completed), select job progress (or similar) from dropdown, screen should show what is required to continue.