after ios7 update, some songs missing from playlists after syncing. They are still on the mac playlists, but wont copy onto my phone. The songs themselves show up on the phone under songs or artists, but the playlists are missing them.
I have been plaged by this for months!!! and nothing worked for me until...
Solution:
plug your phone in and in itunes "remove all music and podcasts" or "unsync" all your audio from your phone. I did this by unchecking the box that said "sync selected songs" so it was like I didn't want any music on my phone.
sync it
now go back and check the stuff you want in your phone and vwala it should re-sync all your old music back to your device.
I hope this works for you like it did for me.
Some songs in playlists are not syncing to phone
