The operating system on Genos (or Tyros) is different from the OS on a PC. Opening the file manager (explorer) on a PC will show every file type that is stored on the drives (if not hidden...)
Using the explorer on Genos will not show all the files on a USB or folder. It will only show the file type of the active mode; Song, Voice, Style... In fact, it will hide all the other types at that moment.
It works by type, meaning; if you want to view Style files, you first need to be in Style mode = activate the mode by pressing the picture Style on the Home display.
Now your system is in Style mode. The only files you can see now on a USB or on the User are Style files, you won't see Songs, Voices, Multi Pads etc, even if they are present in the folders.
If you want to work with Songs, first activate the Song mode by pressing the Song on the Home display (or anything else that activates that mode), otherwise you will never find the files on your USB.
Warning: in song mode you additionally need to select the correct file type: Midi or Audio !!!
Don't think PC, think Genos ;-)
Stijn