I have a frustrating issue where every time I sync my iPhone 6 (latest OS) with iTunes (v 184.108.40.206 and El Capitan) it erases and re-syncs the same 1026 tracks each time. The other 8200 songs on my iPhone behave normally - they don't re-sync each time. I've tried disabling music sync - wiping music from iPhone and then adding all music back. I've also tried disabling smart playlist syncing. Nothing helps so far. Apple has no idea - they just told me to restore my iPhone, which I am loath to do. (I used to have to restore my iPhone regularly to get artwork to sync). I don't see any rhyme or reason to the songs that are re-syncing. Some I've listened to recently, others not for a year or more. Thanks for any ideas!