Eric, I unchecked sRGB already. It was one of the first things I tried. It makes no difference.
Also the washout and color range issue shows up both with built and unbuilt lighting.
The material is extremely primitive. 0 (black) in the specular and the texture is wired directly into the Base color.
I will also point out that trying to exaggerate the diffuse texture in the material isn’t solving the problem and won’t actually be a proper fix. The problem is that Unreal isn’t faithfully reproducing the color range when shown in the viewport. sRGB makes no difference, lighting makes no difference, Film effects don’t fix it because they only try to post-fix/hide the real problem. The only thing I haven’t figured out yet how to change is the gamma itself or the map from HDR to LDR – they are my last hope.