[GAMEPLAY] Mouse Hops to the Top of Screen in Patch 8.6

I am on macOS High Sierra 10.13.3, and as of the latest patch 8.6 any time my mouse is near the my item slots at the bottom of the screen (at the 1, 2 & 3 item slots), my mouse changes locations and goes to the top of the screen. This is absolutely game breaking, in the sense that I cannot play properly as my mouse behavior is unreliable - hence I miss all my skill shots. This is 100% reproducible no matter what I am doing. This also prevents me from using the slide bar in the shop since it keeps flinging my cursor to the top of the screen every time I slide it down.

In ARAM, this issue not only persists but is much worse. I have also noticed that my mouse starts to lag and becomes choppy when trying to click enemy champions in ARAM, and sometimes cursor doesn't even allow me to click to attack enemy champions.

PLEASE look into this issue Riot. All my drivers are up to date, and I've tried full repair a few times to no avail. I will try a fresh reinstall at some point to see if that works but I'm confident its some sort of bug for 8.6 - this has never happened to me in the 6 years I have played this game.