Unable to modify AVR's EDID (I could previously)

[ToastyX]

You're encountering the second driver bug that I was talking about. I don't have a setup affected by this issue, so I don't know what triggers it, but it's definitely an NVIDIA driver bug. Someone mentioned the last driver that worked for them was 528.02, but I started getting reports of this issue around 471.41. Also, installing an older driver without the problem and then upgrading the driver seems to work around the problem for some reason. Since the problem persists after using DDU, it could be triggered by some setting in Windows, such as the last resolution and refresh rate set before restarting, or the driver might be incorrectly expecting something that's not there anymore since reset-all.exe and DDU both clear all the display settings.