How do I fix a problem with the "iCloud Music Library" toggle on/off option under Music settings on the iPhone 6 (iOS 8.4)?

Whenever I try to toggle this option on, it turns itself back off whenever I switch to another app or exit out of it.

I first noticed this when I tried to "Make Available Offline" some more music, in addition to other music I had previously made available offline from Apple Music so that I could listen to songs without WiFi. I would make a song available offline, but then it wouldn't show up in My Music library. When I looked at music settings, iCloud Music Library was off and I became confused because I usually keep this on.

This morning upon arrival to work where I have no WiFi, all the music I had previously made available offline from Apple Music before this problem arose became grayed out and unplayable (which is poo because now I have no music to listen to at work). Just yesterday I could listen to all my music just fine.

This is really annoying because I just want it to stay on but it keeps switching off. How do I fix this?