I'm running bootcamp / Windows 10 on my macbook pro, and using an external Samsung UHD Space Monitor LS32R75, with the 4k resolution (3840x2160).
Light pastel colors are barely visible.
I attempted to fix this by simply adjusting colors, gamma, brightness, etc with the JOG button on the bottom right back side of the monitor, with no luck.
After going in windows 10 Advanced display settings, I noticed the refresh rate was 30,000 Hz... I thought that looked strange as refresh rates are normally 60,000 Hz. Refresh rate of 60k Hz would at least improve motion to be more fluid, so I changed my settings to 60,000 Hz.
Somehow, this setting to the refresh rate fixed the colors. Light pastel colors are now visible. I don't know why, considering refresh rate has nothing to do with color. But if you have the same problem, give that a try.
If anyone has any theories as to why setting refresh rates to 60k Hz fixes color, please let us know! Thanks.