More verbose details under "Other Disk Usage" inside cPanel
Often times users will see a quota mismatch between what they think should be the real usage and what the actual usage is, and this is usually caused by filed owned by that user outside of the /home/username folder. These are typically found listed in cPanel under the "Other Disk Usage" section.
While all the other links at the following page:
are clickable and provide you with more information, the Other Disk Usage option does not. Since the server has this data it should be available as a clickable link - either to display those files on the screen or to download a text file - something that indicates where these files are.