I recently discoverd the offline synching between laptop and iphone. today I made a new playlist consisting of spotify songs and a bunch of local files. Almost all files synched, safe for the last few. When I tried to sync an older playlist as well, the songs show up on my laptop, can be played, but safe for 2 songs (which I synched earlier), none of the local files show up on my iphone, although the phones states he's done downloading all my stuff. I still have 1,75 GB of space. Why does one playlist only synch most of the songs and the other basically not at all?