I have the exact same issue. Only 4 resolutions available. However, I noticed that in the "Adjust desktop size and position" menu when I switch scaling from GPU to Display, I get all the resolutions available again. The problem is this only applies to the desktop and in games only 4 resolutions are available again. The other thing I found is that in the monitor's OSD menu, when I activate Adaptive Sync all the resolutions appear. But when I disable Adaptive Sync I'm back to the same limited 4 resolutions.
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