I cannot take credit for this, i found a post hidden deep in the forum. But it worked for me. I know what your thinking, youve read the posts saying "THIS WORKS FOR ME" and it tells you to turn your firewall off/turn it on and off etc etc. I tried absolutely everything too, and this **bleep** works. Behold, the fix:
3 weeks ago
Hey I too have spent the majority of yesterday and today trying to get my local files to sync. I don't know if all of these steps are realted, but give them a try because it worked for me.
I have Spotify open. So I turned on Personal Hotspot, and then connected my iphone to the computer via usb. The computer should take up this connection. Next I hit file>new playlist, and BAM, my iphone appeared under devices. This might have just been a glitch for me but you never know. Hope it works!