I think I figured it out. And it doesn't appear to be a bug to me, just apple changed the way the iTunes syncs music to the iPhone.
When you used to sync your music before on iOS 6, when you looked on itunes and it would sync the song, it would immediately sync to your phone. But with iTunes 11.1 and iOS 7, it seems to do it differently, at least from my experience.
Now it appears that "syncs" the songs to your phone, but then the "changes have to be applied" and the "items have to be copied". I hope I'm making sense because it's kind of hard to explain.
So this is what I did:
-I restored my phone back factory settings.
-I restored my phone from my latest back up.
-After my apps and photos would sync, it would begin syncing my music and either one of two things would happen.
1) It would immediately show my songs "syncing".
2) It would say "waiting for changes to be applied".
-Now depending how many songs you have, this may take awhile. For myself, I have over 6000 songs so it took me at least an hour.
-At this point go to your phone and go to the music app while it's syncing.
(Now this this the part that's hard to explain.)
Let's say for example you have 6000 songs. iTunes states that it's syncing the songs to your phone, but the songs don't appear on your music app. You just need to be patient! Because for whatever reason, it puts the music in in alphabetical order.
Also when iTunes 11.1 syncs, it would say for example appear that all 6000 songs synced and then be stuck on the "infinite" waiting for changes to be applied stage, and when you look in your phone, only 3000 songs would be on your phone, just be patient because it's still syncing. To prove this, just go alphabetically in your artist list on your music app on your phone while it's syncing and look at the amount of songs in your phone. iTunes will put a song per album for each artist AND then put the rest of the music in the iPhone by artist alphabetically. Some of the artist will have all their songs, most like the ones closer to the letter "a" alphabetically, and eventually you will find an artist who doesn't have the correct amount of songs on their playlist AND all the artist after it won't either. Once you find that artist, concentrate on their amount of songs and slowly but surely, you'll see the # of songs go up. And then so on and so on per artist until it actually finishes the sync. Only then will the whole "infinite" waiting for changes to be applied screen leave.
I hope that made any sense. It's easier to show, than to explain.
