iPhone 5, Music: Albums fragmented

My iPhone 5 no longer displays Artists or Albums properly in Music - instead, many albums have fragmented into multiple listings, often containing only 1 song.

So, for example, if I have an album with 8 songs on it, instead of one listing when sorting by Album or Artist in Music, it can now have as many as 8 separate listings, each listing containing a separate song.

I have a lot of music - my 64GB isn't enough to store all my music so I use the iTunes Match service. And this problem has made it impossible to properly find and sort through for artists or albums.

I tried powering the phone on/off, and switching iTunes Match off on both the phone and iTunes - but it's all still jumbled up.

The only recent change to the phone was an update to carrier settings - I can't imagine that directly interfering with the music app?

Any pointers on how to fix this are much appreciated!