League of Legends, Miss Fortune's ultimate is glitching

Background

I am playing Miss Fortune in League of Legends, and her ultimate is that she stands still in a spot and sends out 17 waves of bullets in a cone in front of her, dealing massive damage.

Miss Fortune's ultimate examples [1]:

Problem

The issue is that often when I activate the ultimate, the character still does the animation and the sound still happens, but no bullets come out and no damage is dealt. Is there a way to fix this?