sion ult causing screen to lock in place and unable to unlock

I've been playing Sion and sometimes when I use the ult it locks the screen and I am unable to unlock it. Hitting Y or clicking the unlock button doesn't work. I'm not sure what the root cause is, and I haven't noticed what situations it occurs in as I've played 20 total games with sion and it's happened 3 times. Just speculation, but it may occur when i use my ult but am not on my screen. but I haven't incurred the bug enough to recognize it yet. I will update this post when possible.