UMG retainer box washing colours out on 3D Widget

I BELIEVED that the submitted answer was the correct fix, but I wasn’t really dealing with the issue at the time. We came back to this a few weeks ago and actually found the same as you, changing it to non-srgb (and therefore the texture samplers in the shader as linear color) had some effect, but didn’t really change much. We actually ended up just compensating for this in our shader. Not a satisfying answer at all, I know.