Malevolent Practice unable to complete

Playing on PS4
Mission Malevolent Practice
Issue: play this mission you have to kill and smash certain enemies however during a fight one of these enemies fell off the edge of the map because of this I can no longer smash him and now cannot proceed with the rest of the mission.
I think this is more bad luck then it is a bug however not being able to complete this mission is annoying.
Otherwise love this game and will complete this mission in new game plus for sure!