Using a Theater Mode that has an 'AlbumTracks' element (like the default 'Rdio Style' Theater Mode) and then playing an album that's in the Inbox and not in the Music Library, results in no track list being displayed (the tracks do show up when they're sent to the Library).
Not sure if this is just a limitation but the issue is not present with the 'NowPlayingList' element, the tracks still show up even if they're in the Inbox but I'm assuming that one is just pulling direct from the current/queued Playing Tracks.
Example of the element in question:
<element type="AlbumTracks" x="40" y="245" width="441" height="800" font="Segoe UI" style="Regular" size="11" rowPadding="10" bg="180,5,5,5" fg="240,240,240" fg2="150,200,255" mouseOverFg="200,200,200" >
<child width="15" />
<child id="Speaker" width="20" />
<child id="TrackNo" align="center" width="47" />
<child id="TrackArtistAndTitle" width="283" />
<child id="Duration" align="right" width="60" />
</element>