Howling Abyss map tower bug

It happened to me a couple of times and i've seen it happen to others as well. On the blue/lower side of the map, when you pass right by the left/upper nexus tower, your champ starts to walk in slow motion, in reverse or skip/stop all while in running animation. Moving forward or backwards does not help, only going sideways seem to be an instant cure.

I first thought it was just lag and it may still be just that, but the bug seems to happen in the same spot every time, just after you pass that tower.