Sion E: Minion dissapears when i launch them

So, when I shout minions, they occasionally disappear and it happens enough for it to be game breaking. I've seen it happen a dozen times in the first 10 minutes The keystones I've seen this happening on are aerys or comet. Not sure if this might have anything to do with it. This really needs to be fixed, not playing him again otherwise. I stole this clip from someone else, but its exactly what happens