Vel'Koz Void Rift Blocking Skillshots

Played a game as Xerath against Vel'koz mid and found that on several occasions my e (the stun) got block (i.e. dissapeared) when it hit Vel'koz's void rift.

This happened when the rift was places at a slight angle but pointing towards me from vel'koz (so almost a straight line in front of me). My e would move onto the area of the rift and as it reached the middle of the rift, it would disappear. This would happen quite close to me so the e would not have reached its max range by the time it disappeared. I am unsure if this is simply visual (i.e. the sphere disappears but is in fact still moving), or if it is actually blocked.

I do not have a video/image to show however I can say that I very rarely ever play against a vel'koz and in one game this bug happened two or three times. To reproduce the bug I would attempt to fine a skill shot (Xerath e or others) at the rift in different orientations.

Thanks, and hope the bug is easy to fix, Atila d hun