The washed out color has nothing to do with my tv settings. The very same TV has a superb color when playing bluray movies, however when playing all 4k movies, the color is like washed out. No problem at all with Netflix 4k.
On my TV (Samsung Series 8) HDR movies are usually quite dark, but the color is ok.
Have you used something like MediaInfo to see what the specs for the file are. especially compared to a file that does show properly. You might find some clues there.