[Gameplay] Attacking enemies inside Kindred ult does not give assists after it ends

I was Karthus in ARAM and used ult. How on earth would it be possible for Karthus to not assist something during his ult is beyond me. The enemy Leblanc was inside the Kindred ult when mine went off and she died immediately after Kindred ult disappeared, but I didn't get any credit for assisting since all I did was damage that didn't kill her. There's no reason this should be the case. Just because they can't die in the ult doesn't mean you shouldn't be given credit for helping to kill someone after the ult is gone. You still assisted and dealt damage.