Bard's Q and different interactions with Anivia wall and Yorick Wall

Hi! I am not sure if it's a bug or not, maybe it's intentionallly done, but does anyone know why Bard can stun Anivia against her wall, but if the stun first goes through the wall it doesn't connect and stun Anivia? In Yorick case, you can stun Yorick against his wall and also you can stun him if the stun goes first through the wall. I found this video where this guy shows it as a proof: https://www.youtube.com/watch?v=j3uQD_eoWsc The moment with Anivia starts at 1:34 , with Yorick at 1:57. In several of my games I played,I would be able to stun Anivia against her wall, but I could never stun her through the wall, unlike Yorick's wall, where it doesn't matter if Yorick gets stunned against or through the wall. If anybody can explain how these things work and their different interactions, that would be much appreciated.