ExCss 4.3.2 ignores custom variables

[Scal-Human]

With the following css

css-metadata {
    --Archetype:    Theme;
    --Name:         Drive-In;
    --Version:      1.0;
}
#ThemeOptions {
    --Theme-font-family:                Segoe UI;
    --Theme-font-size:                  16px;
    --ThemeZoneBackgroundDark-color:    WitheSmoke;
    --ThemeZoneBackgroundLight-color:   #333333;
}
#ThemeCanvas {
    aspect-ratio:               16 / 9;
    background-image:           url("/Theme/DriveIn/DriveIn-01-HD.jpg");
}
#ThemeZoneLeftAd { --ThemeRole: Context;
    color:      var(--ThemeZoneBackgroundLight-color);
    left:       5cqw; top: 40cqw; width: 15cqw; height: 20cqw;
    transform:  rotate3d(0, 1, 0, 10deg);
}
#ThemeZoneRightAd { --ThemeRole: Control;
    color:      var(--ThemeZoneBackgroundLight-color);
    left:       80cqw; top: 40cqw; width: 15cqw; height: 20cqw;
    transform:  rotate3d(0, 1, 0, -10deg);
}
#ThemeZoneScreen { --ThemeRole: Content;
    color:  var(--ThemeZoneBackgroundLight-color);
    left:   30cqw; top: 10cqw; width: 50cqw; height: 40cqw;
}

here is what a simple test gives:

Stylesheet
  StyleRule
    IdSelector #About (Id)
    StyleDeclaration
  StyleRule
    IdSelector #ThemeOptions (Id)
    StyleDeclaration
  StyleRule
    IdSelector #ThemeCanvas (Id)
    StyleDeclaration
      AspectRatioProperty
      BackgroundImageProperty
      Property aspect-ratio: 16/9
      Property background-image: url("/Theme/DriveIn/DriveIn-01-HD.jpg")
      Child AspectRatioProperty: ExCSS.AspectRatioProperty
      Child BackgroundImageProperty: ExCSS.BackgroundImageProperty
  StyleRule
    IdSelector #ThemeZoneLeftAd (Id)
    StyleDeclaration
      TransformProperty
      Property transform: rotate3d(0, 1, 0, 10deg)
      Child TransformProperty: ExCSS.TransformProperty
  StyleRule
    IdSelector #ThemeZoneRightAd (Id)
    StyleDeclaration
      TransformProperty
      Property transform: rotate3d(0, 1, 0, -10deg)
      Child TransformProperty: ExCSS.TransformProperty
  StyleRule
    IdSelector #ThemeZoneScreen (Id)
    StyleDeclaration

Mention that there is a StyleDeclaration for css-metadata but it is empty.