option_groups_from_collection_for_select with include_blank option

I have some trouble here trying to include an include_blank option for 'option_groups_from_collection_for_select' I would like to have include_blank option but have the currently selected value displayed instead of a blank selection on update action. I have tried this here but it still shows blank.

    select_tag(:candidate_source, option_groups_from_collection_for_select(grouped_candidate_sources, :second, :first, :id, :source), { :include_blank => true, :selected => :source })