Cassiopeia ult bugged with Kha'zix

With Kha'zix whenever I have jumped behind Cassiopeia to attack she ults in front of her and then I am stunned even though you are suppose to be when you look at her you are getting stunned. This occurred every single time I tried to jump behind her and I am for sure sure that I am behind her and she still manages to stun me.

Hope this helps,

~Wantedhorse