Is this a bug of mordekaiser Q and if it is riot fix it fast plz

well is this a bug when if you use mordekaiser r on an enemy then use your Q a few mili seconds before your ult end ( and the mace must smash at the ground in the middle of the end of the ult ) then the enemy will get no damage. If this is a bug then fix it riot i have met it 5 times