I've only just started and it only happens to some of them. I tried to do what you said, so I put one year for all songs but it's still splitting it up. Everything looks OK in Properties, and yet it gets all weird when loading it to MusicBee. Yes some are compilations and fan made, but I've also got fan made ones that are OK, that end up in one album. I don't know what's going on and how to fix it. I've also got compilations (real ones) that are OK, end up in one folder.