Rarely do the BE's ever have any control. Usually there is a production mixer (or 2) that mix the live even. Often times BE's can offer input during rehearsals, but this is more of a courtesy to the artist and to guide production engineer in the subtleties of the artist.
Sometimes the broadcast truck gets the mix of the band minus vocal, and separate vocal and announce feeds. Perhaps this is where any discrepancies exist? I am not watching the broadcast, so I cannot comment on specifics.
More than likely it has something to do with the technology after it leaves the broadcast truck.