Sort Albums by Artist using MPMediaQuery

I'm trying to access the user’s local music library using MPMediaQuery to sort the results in the following manner:

Artist A (sorted alphabetically) > All of Artist A's albums, sorted alphabetically
Artist B (sorted alphabetically) > All of Artist B's albums, sorted alphabetically
Artist C (sorted alphabetically) > All of Artist C's albums, sorted alphabetically
...

My query is structured thusly:

MPMediaQuery *albumsQuery = [MPMediaQuery albumsQuery];
albumsQuery.groupingType = MPMediaGroupingAlbumArtist;

But the issue is that while the aforementioned mostly works, only first album per given artist is returned. That is, only one of Alt-J’s albums is returned, not the two that exist in the library.

Why is that? And how can I structure my query to return the desired result?

EDIT: This is how I’m accessing the albumsQuery:

AlbumCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:CellID forIndexPath:indexPath];
MPMediaItemCollection *collection = [_items objectAtIndex:indexPath.row];
MPMediaItem *cellItem = [collection representativeItem];

Where _items is an NSArray that contains the MPMediaQuery’s result.