UI Toolkit color gradient not applying to Label text when Outline Width is set to more than 0

How to reproduce:

1. Open the attached “IN-139035_unity-bug-project.zip” project
2. Open the “SampleScene”
3. In the Project Window press on the “UIDocument” GameObject
4. Set the UI Document component’s Source Asset property field to “UxmlFoo”
5. Open and observe Game view

Actual result: "With gradient and outline" Label text only has an outline
Expected result: "With gradient and outline" Label text has both an outline and the gradient

Reproducible with: 2023.1.0a1, 6000.0.72f1, 6000.3.13f1, 6000.4.2f1, 6000.5.0b3, 6000.6.0a2

Reproducible on: Windows 11, Ubuntu 24.4.04 LTS
Not reproducible on: No other environment tested

Workaround: Wrapping the element in a <color=></color> tag, f.e.:
<color=yellow><gradient="gradient-vertical">With gradient and outline</gradient></color>

Notes:

• “With gradient and outline” is parsed from: <gradient="gradient-vertical">With gradient and outline</gradient>
• Setting Outline Width > 0 in the UI Builder on the Label, in the Text section, causes the <gradient> rich text tag to not apply to the Label text
• If Outline Width set <= 0 then the gradient rich text applies to the Label text
• Reproducible in a build

 

Link to forum post: https://discussions.unity.com/t/ui-toolkit-text-more-text-styling/1715066/3