To see all files that are part of either the File Catalog or Files on Computers page, set the Max Age = none.
Additional Information
On the File Catalog and Files on Computers pages, setting the max age to 2 weeks (for example) will only show files discovered within the last two weeks. If you are looking for a "complete" picture of files on endpoints, you will need to leave the max age set to none, so as not to filter out any results.