Yorick ult bug not pushing or following just sitting there

I was playing my main champion and In a ranked game I encountered a bug that lost us the game... I used my ult to get a kill near my tower and then it just stayed there and when it got minion aggro, once it didn't get it anymore, it would go back and sit at the corner of my tower. It has also happened a few times where the maiden will just sit somewhere and not move from that location.