That’s by design. The slider isn’t part of the stored settings. You will also lose it’s value when opening the image again later. The effect is kept though: it scales the actual curves.
@houz What’s the rationale behind it? I mean, I can save the changes in other equalizer settings and when I open the image again I can proceed from where I left them. Why can’t I do the same with the mix setting?
The slider was added as a convenience tool to help you modify the strength of the effect. It is not a module parameter in itself; when you leave darkroom mode all changes will be consolidated into the spline curves.
@everyone I got it, thanks. I was giving too much importance to that slider value, but what really matters is the curve. The slider is just a means to get a curve that fits my needs. Once I get that curve, it’s not important to save the old curve + slider value, just keep the resulting curve.