When albums get un-albumized and track split, I nearly always find that there is a weird bit of track-meta that has thrown the tracks out. In these cases I do a quick tidy in mp3tag and then they go in straight.

e.g. the album title at meat level is not identical. This is quite common in downloaded albums where the record label has been sloppy with the tags.

The re-grouping of tracks into album always works pretty well if you are confident all the album tracks are present.

Rgds,
Nick