Ashe E Going Opposite Direction

My boyfriend plays Ashe a lot and I would always be supporting him. I would ask him to E across the map for vision, but every so often it would go into the opposite direction. At first, I thought it was just him being a tard and clicked the wrong direction but then he did it again and the same thing happened. For example, he would E towards top lane but it would just go to the right and towards the edge of bot lane instead. I decided the to play Ashe for a few games and the same thing happened to me. So I know for sure it's not my boyfriend and it's probably a minor bug.