Mordekaiser E casting in the wrong direction.

HI. I have this issue with Mordes E where sometimes it will cast way off from where my mouse was pointing when I pressed the button, sometimes it will even seem to cast a split second late and in 90 degrees the other direction. This has been going on for a long time for me so I don't think it's human error or I would have figured it out by now, Is there possibly something wrong on my end or is this just a bug? Has anyone else experienced the same thing?