If you're using the preview build then you should be using the winamp provided local library plug-in (ml_local) which has the associative sorting wanted.
The replacement plug-in (ml_ll) which is the only plug-in in the current betas has basic associative sorting within the local library views but doesn't in the preview build as that was a mistake to include it as part of the preview build in it's massively incomplete state.
-dro