How did you resolve this? I'm having the same problem. Even when I set it to add new files to the library, not the inbox. Even when I selected all files in inbox, and sent them to the library, the library is empty. Even though the playlists show up in the playlists tab, the "music" tab is empty.
EDIT: * Never mind, it just took a L O N G time to update the library. Anyone else with this problem should tell it to scan, and then go make coffee or tea or something, if you have a large library. *