I recently tried to sync 3 albums to my iPhone 5 via local files and found that only one of them would sync properly.

The albums I tried to sync were:

In Rainbows by Radiohead

The Eraser by Thom Yorke

Amok by Atoms for Peace

Only In Rainbows synced properly. I also synced a few random tracks from other artists, and those worked fine as well. The playlists I created for Amok and The Eraser appear on my iPhone, and list the correct number of tracks from the list of playlists, but once I tap into the playlist, it's blank and tells me to add tracks. I have no trouble playing the local files within Spotify on the Macbook Pro I added the tracks from.

I know that Thom Yorke has pulled all music that wasn't created through his old Radiohead label from Spotify, but does Spotify go even beyond that and prevent uploading the music via local files as well? I can't think of any other explanation.