[GAMEPLAY] Jarvan IV's ult being walked through

I have had 3 separate instances where I have used Jarvan IV's ult and those running away have 'slipped' out through a crack or seam. It first happened against bots so I thought maybe they just had a glitch, but then it also happened in an ARAM match. I do not have a screenshot or video but it has happened enough that I don't believe it will be hard to duplicate.