Darius + Vel knock off map bug

Basially Vel's knock up is not working as it should. If paired with another knock up so some degree and the timing is right, the person in the first knock up hit by Vel's knock up, they are sent airborn off the screen into the sky for a few seconds. This happened in a game i was playing where a Darius pull the enemies Lee sin directly above Vel's own E and went it went off lee flew off the screen skyward. My friend also informed me of this happening with Thresh as well. This should be looked at