Ashe ult bug

Used ashe's ult from base and it went all the way to the first enemy tower, but then hit minions and stopped. There were no champions that got hit by it, or were even close enough for it to hit. It literally blew up on the first minion it was supposed to go over. I have no idea if it repeats in other games with her or what exactly activates it. I just know it happened to me in my last game.