Anivia Ice Wall (Crystallize) Bug

Occurred twice throughout my game involving the opposing teams Fizz and Sivir. the first time occurred when fizz jumped and landed by the top tri bush, i placed my ice wall in front of Fizz to cut him off causing him to be out of position so Lee Sin, Gnar and i could kill him or get his flash to be blown for him to escape, instead i see him walk through my ice wall just after i had placed it, fizz had already landed from his playful trickster and just walked on through. The second incident was around dragon pit, when i caught Sivir and Darius out and split them with my ice wall and Sivir just walked on through just like Fizz did allowing her to get out of the situation she was in (she did not spell shield either, and that shouldn't negate my ice wall from stopping her), again neither of these incidents involved flash being used by Sivir or Fizz. I seemed to notice that if Anivia's ice wall gets placed to close to the champion, but not directly on them, it seems to allow the opposing champion to walk on through the ability. Not sure if it's a bug or a glitch, but those 2 plays could of changed how the game was paced out.