What drivers are you on? The latest drivers are 566.36 and I want to say the whole 56X branch had some workarounds for sync issues with 24H2.
For instance, from the reddit post for the 566.14 drivers:
- Windows 11 24H2 requires MPO support enabled to reliably support DXGI window capture, this impacts applications such as Lossless Scaling and Magpie when using DXGI to capture
- Windows 11 24H2 ALT-TAB black screen is a Microsoft Issue and fixed in KB5046617 (November 12th) - NOTE: may break hardware composition / hardware flip and still be a gradual feature rollout
- Windows 11 24H2 on some systems have crashes when launching games, stutter issues, RTSS related crashes, exclusive fullscreen game ALT-TAB issues and crashes with overlays enabled in games. Other GPU vendors (AMD/INTEL) are also impacted
- Windows 11 24H2 WDDM (Windows Display Driver Model) 3.2 and DirectSR (Super Resolution) driver support officially started with the 560 mainline releases
Also, any apps that can do overlays might be causing issues, even if they aren’t enabled. Like for instance, if I accidentally leave RTSS graphs running and open UE, it causes chaos and I’ll have a bunch of graphs popping up all over the place (even the editor loading screen before the editor opens). Check every running app to make sure none of them have overlays enabled.