How do I download music for offline play on an iPhone?

[Kmg_24]

Using app version 5.7.0.1055

I have read the offline music tutorial which speaks of a "Make Available Offline" slider that if used will show download progress and an icon when songs are downloaded locally. Maybe I'm blind but I can't find that anywhere. I see a slider at the top of albums that says "Download" but pressing it doesn't seem to do anything. The album gets saved to my library but when I go offline all the songs are greyed out and prompt me to go online to play them.

I must be doing something wrong because the rest of the app is very intuitive. Could someone help me out?

FYI I am trying to do this purely with an iPhone and no PC involved. Thanks!

[peakplaylists]

Could you send a screengrab of the spotify playlist you're trying to sync for offline? 

Are you connected to wi-fi whilst trying? It will only work if you're connected (won't work off just phone network 3g/4g)