Ashe Ult Sometimes Goes through the target

So i've witnessed this two times, which is why i have decided to make a post about it now.

The first time i was playing Ashe in a hexakill game. I fired my ult from the spawn of blue side towards the first bot tower of the purple side. I was in game with a friend on skype at the time. We both witnessed the arrow go through three individual champions when traveling through the lane to off screen. Another player commented on it, and if i recall correctly they were on our team. At the time i of course very confused, but i figured it was gonna be a one time thing, or if it was a bug people already knew about it.

The 2nd time was in an ARAM that literally JUST finished. I was playing Shyv and we had an Ashe our our team. She fired her ult (at ~10:00 from looking at chat) from between the two outer towers towards purple side. The arrow went through a enemy teemo who was standing still auto attacking the wave. I said "wtf." Ashe talked in all chat, but not much was said. I only mention that to show that it wasn't just me who saw it, aka it wasn't lag on my side making it look like it hit and it did not.

So yea, i haven't seen this with other ADC ults recently, just these two games with Ashe. If I have another ashe in my game in the future i'll try to pay attention to the conditions that create this case.