Why does iOS keep deleting some of my music and switching to cloud version?

[Engram]

Noticed this problem on iOS7 and still have it on iOS8.

I purchase an album, and sync the entire thing to my iPhone 5S 16GB with iTunes. A few days later I go to play the album and notice that a few tracks are showing the "download from cloud" icon, indicating that they are not being stored locally.

Why?!

Does iOS auto-delete music if you run low on space? I'm not using iTunes Match or Genius. I have iTunes configured to sync "All music", not by playlist.

 

[Kainz]

I can't help with the problem but this is what totally put me off using my iPad3 (iOS7) for media purposes, and one of the two reasons I'm moving to an android tablet as soon as a decent one becomes available (Nexus 9 in October I am looking at you).

I have more or less moved away from iTunes reliance completely on my iPad. Recently I synced some films/tv shows to the device as I was spending the weekend up north. Afterwards I verified that everything was on the device and yep it was. Imagine my surprise 8hrs later when I went to watch some films in my hotel room and saw nothing but cloud icons everywhere on all my media.

I had a ton of space on the device (64gb capacity with 30gb free) so it wasn't a space issue.

 

[Engram]

At least I'm not the only one! It's bizarre that I can't seem to find anyone else discussing this though. Doesn't help that there's loads of hits for the U2 album fiasco, if you start Googling "ios cloud music" etc.

P.S. As annoying as this is, it's not enough to send me to Android.