[GAMEPLAY] Cursor Leaves Game Screen Multi-Monitor

For the past 2 weeks or so, every match of league I play without fail lets my cursor 'leak' out of the game screen onto my second monitor in the middle of any given match. What I mean by that is, at the start of the match, my cursor stays within the game boundaries and I can use the edges of the screen to properly move the camera around without any problems. But, after a minute or two, the right edge of the game window stops acting as a wall, and my cursor will 'leak' out onto my second monitor.

You can imagine how frustrating that is, since once the cursor leaves the game screen, the camera stops scrolling at all, and moving my cursor back into the game window replaces the in-game cursor with the windows cursor. My solution so far has been to click once outside the game, on whatever window I have open on my second monitor (Discord/Chrome/Steam), then alt-tab back into the league window and click in game. This locks the cursor onto the game window for another few minutes, before it suddenly stops caring about that right edge against and lets it 'leak' out again.

Over the last two weeks, I've tried a lot of things to fix this problem, thinking it must be on my end as there isn't any other complaints of this in league. I've tried things like:

1. Perform full repair of league client
2. Use DDU to uninstall all my old graphics drivers and reinstall the latest (Nvidia)
3. Fresh install League
4. Install third party program that is supposed to lock the cursor onto a given monitor with a macro (Dual Monitor Tools). This was the solution others gave that had the problem in other games, but not in League. Testing this proved to work in everything except league. When I would use the macro on the regular desktop, the cursor was locked onto whatever monitor it was currently on like the program is supposed to do, but if I ever used it in league, it would only last a few minutes before it stopped working without me pressing the macro again to unlock it, and the cursor would leak onto the other monitor once again.
5. Have only league running
6. Play in Fullscreen/Borderless Fullscreen/Windowed (I usually do Borderless Fullscreen with no problems, until a few weeks ago when this issue came up. Regardless, none of the other options worked.

So, I'm at my here trying to fix this problem. Any help is greatly appreciated, my MMR and LP will thank you. (Though I probably shouldn't be playing ranked knowing this is an issue).

Steps to reproduce:

1. Get into any league match
2. Wait 2-3 minutes
3. Cursor escapes league (7 years and I still can't)

Thanks! [slayer-jinx-catface]