UMG Regression - "Menu Border Brush" of Combo Boxes No Longer Support Translucent Blend Mode

[GuyEP-Modulate]

Summary

It would appear that the “ComboBox (String)” control (available under the “Input” section of the UMG Designer) no longer properly renders menu borders that use translucency in Unreal 5.6.

Please select what you are reporting on:

Unreal Engine 5.6

What Type of Bug are you experiencing?

UI/Tools

Steps to Reproduce

1. Create a material (e.g., M_BugRepro) that uses a “Material Domain” of “User Interface” and a “Blend Mode” of “Translucent”.
2. Edit the material blueprint from step 1 so that a portion of the material output is opaque and filled with one color, while the rest of the material is translucent/transparent. For example, you could use the GeneratedRoundRect function, as shown in A simple material that demonstrates opacity for UMG posted by anonymous | blueprintUE | PasteBin For Unreal Engine.
3. Create a new UMG widget blueprint (e.g., UBP_MainUI).
4. Add an overlay to the new widget blueprint from step 3.
5. Add a “ComboBox (String)” control to the overlay, and modify the horizontal and vertical alignment properties so it’s centered in the overlay.
6. Under the “Content” → “Default Options” property of the combo box, define several default options (e.g., “Alpha”, “Beta”, and “Omega”).
7. Under the “Content” → “Selected Option” property of the combo box, enter one of the options from step 6 (e.g., “Beta”).
8. Set the “Content” → “Content Padding” property of the combo box to 10.0 to give the text some breathing space.
9. Under the “Style” → “Combo Button Style” → “Menu Border Brush” property of the combo box:
   1. Set “Image” equal to the material from step 1.
   2. Set “Image Size” equal to 64x64.
   3. Set “Tint” equal to (1.0,1.0,1.0,1.0) (opaque white).
10. Modify your project to trigger the UMG widget to appear (e.g., in the level blueprint for your main map, implement Begin Play, use it to construct the widget, then add the widget to the viewport, and set the mouse cursor visible on player controller 0).
11. Launch the project in a separate editor window.
12. Resize the window so the combo box is comfortable visible.
13. Click the combo box in the UI to open the drop-down menu of combo box options.

Expected Result

The menu border should be translucent, like it is in Unreal 5.5.

Observed Result

The menu border is black anywhere there is translucency/transparency in the material.

Platform(s)

Windows 11 24H2 26100.4202

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