Yorick Minions vs stealth

So I was playing Akali top vs Yorick and I noticed that if Yorick sends his minions at me going into my bubble did not matter to his minions. They kept attacking me in stealth and allowed Yorick to know my exact location the whole time. The same happened for his ult minion as well. Maybe I'm wrong, but I feel like this is massive bug that destroys stealth champs.