"Available Offline" not working correctly

I recently received a new Iphone5 (replaced my old one due to battery swelling) and it had the latest IOS installed which includes the new My Music app. I have been scratching my head ever since I got the phone on how to make my music available offline. Every time I think I have it done, the phone seems to go back to a state where 200 or so of my songs go back to being not available. And it's never the same songs. Even the songs that show up available offline, do not have the phone icon next to them. I test this by going into airplane mode.

I tired going into ITunes and downloading all music not on my phone. Then I placed all of my songs into a playlist and tried making that available offline. But it always seems to randomly go back to having certain songs not available offline.