The most common cause for this is that you've sent something to print in a page size that the device does not support. Make sure you send it in A4 (or A3 if required) – check the document size settings on your PC.
Another possibility for this occurrence is that the print device is busy processing a very large document. Press the‘job status’ button second up from the bottom, left of the touch screen, on the Xerox device you’re at – this will show you jobs processing. It may be your print job that is taking time to process, or it may be that someone else has a job processing ahead of yours. In both cases . . . be patient! If you do not want to wait for your job to process you can cancel it - select it via the 'job status' button, then select 'delete'.
A print job will also vanish and not be printed if the cost of printing it exceeds the amount of money on your account - if this occurs you will automatically receive an email telling you this. The job will reappear as waiting next time you swipe.