I'm also having this problem for over a month. I sent this mail to Gizmodo:
"
I can attest that I also have the problem of my phone not syncing big playlists anymore with iOS 7. I have a 64GB iPhone 4S which I paid 850 euros for (just to get a lot of storage) and now the phone is 3/4 empty because of this bug. It has already been more then a month, and like many customers, I have sent feedback to Apple but have gotten no response.
Maybe this is of use, this is everything I already tried to get this problem solved:
- I had a completely manually managed iTunes Library. I made a completely new library, that I let iTunes automatically manage (copy to iTunes Media + put it in the right folders). I use to do this all myself, being a bit neurotic about organisation, but I noticed that I could save time by letting iTunes do this for me, especially since I already checked 99 percent of the meta data of my music collection. So it's a completely new library, but with the same playlists etc.
- Removed all the voice memos on my iPhone, because I heard that sometimes could give problems.
- Restored from an iCloud backup. Many many times. Then syncing again starting from zero. Did not help.
- Changed the name of the MediaLibrary.sqlitedb file on the iPhone (I don't have a jailbreak, I did it trough the OSX program Phoneview). This should have iTunes make a new Library on the iPhone. It was still stuck on the same steps with the same playlists.
- I updated to Mavericks, with iTunes 11.1.2 and to iOS 7.0.3, thinking this 'updated' setup would relieve me of the problem. Again, I was wrong.
- I dragged all the 48.000 music files in a utility called MP3 Scan and Repair. It gave me small errors on about 8000 of my files, some of which are never noticeable, or it would cause a song to prematurely stop or skip. I let it fix all those 8000 files, and lost about 75 percent of the artwork of those files in the process. I spent a day fixing that problem by checking which files had their artwork removed, and looking up new artwork on the internet, updating it manually again.
So as you've seen, I already tried *a lot* of measures to getting this problem fixed.
Maybe this can help if you are writing an article about it.
One thing that I DID NOT try yet, is setting up my phone as a completely new iPhone. Reason being that I'm not going to loose 4 years of text messages because Apple has a bug in their software.
Hope this can be of any help."
Kind regards,