Here is a list of things to do to investigate why your SharePoint site is not displaying the files in a document library properly:

1. Check the settings in the document library – Open the document library and check settings like the View settings, or the sort order.
   Talk to the administrator to make sure you are using the library in the correct way.
2. Check other Libraries: – Look over other document libraries to see if the same issue is occurring.
   Ensure that a library isn't set up differently from others. Talk to the administrator if needed.
3. Check permissions: – Make sure that you have viewing permissions on all documents in the document library.
   Go to the documents directly and find the Sharing option. You should be able to view if it is set to can view.
4. Check for updates: – Check to see if you need to update SharePoint or related application for it to work correctly.
   You may need to re-install or upgrade certain plug-ins or browser applications.
5. Contact IT or SharePoint Support: – If all else fails, contact IT and SharePoint Support for further help.
   They may be able to pinpoint why your document library is not displaying properly.