Gameplay Issue with Yasuo's Wall.

I was playing as Katarina and the enemy team had a Yasuo . His wall literally REMOVED my knife from the ground two times in the game. I think this is a bug because, if the wall is meant to stop projectiles,except lasers, it should not be able to remove any kind of ground spell/effect. If it's NOT A BUG i would like to see whether it de-activates or removes any of the following: Zigg's W, E, Syndra's Ball, Cait's/Nidalle's Traps, Shen's Sword, and if we want to overeact to it: Trundle's Pile, Anivia's Wall or The item tha heals in aoe: . I would like to mention that i'm not talking about the cancellation of the knife's throw,which is absolutely fine,but having already been on the ground before the activation of the wall.