can't sync after iOS8.4 update
in iTUNES, the SYNC button is disabled, and I cannot sync at all.
iPhone 6, iOS 8.4, cannot sync to MacBook Air
Make sure that you are signed into the correct Apple ID on the iOS device that you are signed into in iTunes on your computer. Also make sure that you do not have any restrictions set on the device that would prevent something from syncing.Settings>General>Restrictions on your phone. Check the Summary tab in iTunes and make sure that you don't have Manually Manage Songs and Videos selected.