You need to post more details. What compilation grouping function? You mean the “concat compilations” metadata wedge, which changes the real Artist to “Various Artists” on all the tracks (and puts the Artist in the Title of the song)? It seems to work for me… though I don’t like this feature very much.
Or just the iTunes’ Compliation flag? Or Firefly’s “compdirs”, a directory based equivalent for the Compilation flag?
What client are you using? (iTunes doesn’t need the concat wedge, since it has the ability to group flagged Compilation tracks automatically. SoundBridge, for some unknown reason, doesn’t support this currently.)