Wrong count of total results using Sprunje with extended query and GROUP BY

when I try to extend a Sprunje query using a group by like this:

$sprunje->extendQuery(function($query) use ($start, $end){
      return $query
        ->select('a.*', 'hc_v.date', 'hc_v.id as id_v', DB::raw('COUNT(*) as num_v'), 'a.id as id_a', 'a.name as az_name', 'm.id as id_m', 'mt.desc as mtdesc' )
        ->join('hc_b as b', 'id_b', '=', 'b.id')
        ->join('hc_m as m', 'b.id_m', '=', 'm.id')
        ->join('hc_a as a', 'm.id_a', '=', 'a.id')
        ->join('hc_mv as mv', 'hc_v.id', '=', 'mv.id_visita')
        ->join('hc_mt as mt', 'mv.id_mt', '=', 'mt.id')
        ->whereBetween('hc_v.date', [$start, $end])
        ->groupBy('a.id', 'mv.id_m');

    return $sprunje->toResponse($response);

then the count and count_filtered properties into the response are wrong, because they are related to the number of results before grouping (eg. before the group by the select retrieves 26 rows, but when I group them I should have just 1 row). Items in rows are correct, just the counters are wrong.

Please, could you check?