I have an iPhone 5 iOS 6.1.4 and using a Macbook Air. I am a premium user.
I have read all the support threads and none of the fixes seem to be working for me.
I am connected on the same wifi, but the iphone will not show up under the devices tab on the application on my computer. Thus, any local files I try to sync offline aren't working. Any songs that are available on spotify that I sync offline works fine, although the sync does take an extremely long time. But I'm mostly frustrated with not being able to sync local files.