MPO/Gsync problem

[sena16]

I’ve been having issues for a few months with MPO and G-SYNC in borderless fullscreen.
My setup:
Windows 11
B550 Aorus Elite
Ryzen 5 5600
32GB RAM (3200MT/s)
RTX 5060 Ti 16GB (MSI)
I keep MPO enabled because it allows G-SYNC to work in borderless mode without issues. In the NVIDIA Control Panel, I have G-SYNC set to fullscreen only (not using the fullscreen + windowed hack), and I use the G-SYNC indicator to confirm when it’s active in-game.
The problem is that, since switching to Windows 11, MPO randomly crashes and disables itself (Special K shows “1 plane, OFF”). When that happens, I lose G-SYNC in borderless mode. The only way to fix it is by reinstalling the GPU driver.
I’ve tried isolating the issue, and it seems to happen mostly when my brother uses the PC. He usually plays:
Limbus Company
Roblox
The Binding of Isaac
Streams his screen on Discord
I’ve already tried:
Disabling hardware acceleration and overlay in Discord
Forcing G-SYNC off via NVIDIA Profile Inspector for those games
But the issue still comes back eventually.
I’ve read that Special K can restart the driver and restore MPO, but that doesn’t work for me—only reinstalling the driver fixes it.
At this point, I’m out of ideas. Any help would be appreciated.

[RealNC]

MPO isn't necessary for it to work, as long as you keep overlays disabled. Biggest offender right now is discord, which keeps the overlay enabled at all times and just makes it invisible, but it still prevents direct flip mode without MPOs. If you quit discord, does it work then?

I have MPOs completely disabled and direct flip works at all times if I make sure no overlays are enabled. Other than discord, game bar might also be responsible for this. As well as other software that has an overlay.

Also, are you using more than one display? On Nvidia, the driver chooses the display that gets MPOs randomly with no way to configure it.

[sena16]

I'm using only one monitor. Even if I close Discord, the problem still persists.
I tried to isolate the issue, and it seems to happen only when my brother comes over, uses my PC, and streams the entire screen while playing. Could that be what causes MPO to stop working? Because whenever I lose MPO, I also lose G-SYNC in borderless mode. Discord, NVIDIA, and Game Bar overlays are all disabled here.

[RealNC]

And a simple reboot doesn't help? Not fast restart, but full Windows reboot that actually reloads drivers and processes instead of suspending them and resuming them. You probably need to disable the suspend and fast startup features in Windows.

[sena16]

That doesn't fix it. I already keep Fast Startup and Suspend Mode disabled by default, and restarting doesn't help. Honestly, I've never seen anything like this before, and I only opened this thread because I couldn't find any answers online. Even after a clean Windows install, the issue persists. It's so specific that I can't consistently reproduce it to isolate the cause. All I know is that it only happens when my brother uses the PC—when he was away for a month, the computer ran perfectly the whole time.