The demo app only has files that it has created itself. Maidsafe explicitly chose the design to have non-shared (not to be confused with “private”) files be app-specific. You can spoof yourself as the demo app (same ID, vendor, etc) and you’ll see them. I have asked them below to change how they were doing it w/ the /public stuff:
But it has unfortunately gone unresponded-to. You should be able to use “shared” files to see files across apps, but the demo app does not do this. Unfortunately the differences between public, private, shared, and non-shared are woefully underdocumented.