Anivia wall renders kassadin immobile and incapable of ulting[GamePlay]

I just got done playing a game as Kassadin Vs Anivia midlane and encountered a ridiculous bug. Anivia hit level 3 and immediately placed her wall on top of me as i was walking away from her. immediately upon cast i became immobilized as if the wall were a Morgana snare. this left her free to autoattack and spam spells on me until i was dead i was unable to move the entire time until i died. I said "WTF your wall is so bugged" in allchat, and Anivia laughed, and responded "yeah haha it only works on kassadin" this leads me to believe that it is something she can consistently replicate but only for this matchup. It happened again when i was lvl 6 and i was even unable to use riftwalk to escape it. Essentially every time i got within wall range of anivia (no matter my level or spells i used) she attempted this "snare" bug with 100% success rate and it was incredibly frustrating and ruined my lane for me

this bug must be fixed ASAP because i'm sure kassadins everywhere are getting exploited by this bug