[GAMEPLAY] Kayn- Ult Death Bug

In a recent custom 1v1 on the Howling Abyss I was playing Riot K-9 and my friend was playing . Twice in the game when he ulted me he had an unexplainable death. The 1st death was when he ulted me and upon exiting he died. No skill, ability, spell, or auto hit him. He just died. There was no dash out animation, just his death animation. The 2nd death was when he ulted me and upon entering he died. The animation for his ult still went off though after his death animation. I downloaded the replay and slowed the frames and this was confirmed as what happened. (If there was a way to post the file I would. I am in the Boards Moderation discord so I guess that's a way. I could also send it by email.) I hope this gets addressed and I appreciate Riot for taking the time to read this post.