Silverlight 3 DataGrid (w/ PagedCollectionView) RowGroupHeaderStyles not reapplied on sort

Question

I am trying to use a DataGrid with hidden group row headers (so that there is a sort boundary). My style simply sets the visibility to collapsed (and I also am setting the SublevelIndent to 0 during the LoadingGroup event). Initial display is exactly what I want, but the data grid is sorted the appearance is unstyled, and the default indent is apparent. (When debugging the style is still present, and the sublevelindent still says 0).