Ok so I recently had to get a new hard drive on my wonderful iMac. To recover my songs, I used a program called iPod Access v4.4.1 to retrieve my music and playlists from my iPhone and transfer them to my iPhone. So in my iTunes the settings seem fine. Under the iPhone preferences, I have "Sync Music" and "Entire music library" selected. All songs including those in playlists are checked. After I sync my iPhone, I see that all the songs transferred over. The playlists all synced as well. However, when I click on the playlist on my iPhone, no songs are present. I go back to iTunes and click on the same playlist and all the songs are there. So what is going on?!?!