iTunes won't sync updates to playlists to my Iphone
I manage all of my music on my iPhone through playlists. When I try to add songs to a playlist and sync the phone, the songs appear on the phone as if they've synced properly, but they are grayed out and do not play. The only work around I have found it to completely remove that playlist from the phone and add it again. Is there any fix for this?
I'm using an iPhone 6s running iOS 9.2. My Macbook Pro is running OS 10.10.5 and iTunes 12.3. I don't really want to upgrade to 10.11 if I don't have to. I just want iTunes to work.
MacBook Pro (15-inch Early 2011), OS X Yosemite (10.10.5)