Gulp-cssmin breaks hexa color code with tranparency

Question

I'm using gulp-cssmin to minify my css but even if I apply the required options from the doc :

function minifyCSS() {
    let options = {
        compatibility: {
            colors: {
                hexAlpha: true, // controls 4- and 8-character hex color support
                opacity: true // controls `rgba()` / `hsla()` color support
            }
        },
        showLog: true
    };
    return cssmin(options);
}

I'm still getting the hexa color code wrong :

{background-color:#0001f}

instead of what I want :

{background-color:#0000001f}

Does anyone knows how to handle it ?