Seems there's a bug in recent driver versions where displays over USB-C are not recognized properly.
EDIT: Driver version 18.104.22.16878 indeed fixes the washed out colors. It didn't add the missing options under General Settings, but it's a step up.
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Yeah, same here! My USB C monitor now matches the colors on the HDMI monitor with the 4678 driver!
As you also mentioned, the option to enable full quantization range is missing on the USB-C connected monitor, but it seems it is applying it.
Sidenote: How do you prevent window from auto-updating the driver?