Yasuo Windwall

Have played against a yasuo mid 3 times in a row and have noticed that if you are in close proximity to Yasuo when he does windwall and it animates behind you as veigar it still blocks your abilities. I figured that oh i just didnt wait long enough until it was completely behind me the first time, so every successive time I waited just a bit longer but to no avail. I should have taken screen shots but int the moment you don't think about that. It happened multiple times in three different games. I don't know where veigars abilities start but i do know that the windwall appearing behind me shouldn't block abilities that go forward...