Reproduction steps:
1. Open the attached “IN-104652_UIToolkitSpriteBug.zip“ project
2. Double-click to open the “Assets/SpriteBug.uxml“ asset inside the UI Builder window
3. Select the ‘VisualElement’ inside the Hierarchy
3. Inside the Inspector, go to the ‘Background’ settings tab
4. Change the ‘Image’ field’s type to ‘Sprite’
5. Select any, but the first, sprite, for example ‘UI_Exit.png'
6. Observe the Viewport

Expected result: The selected sprite is seen
Actual result: 'UI_Camera' sprite is shown, but not the selected sprite

Reproducible with: 6000.0.54f1, 6000.1.14f1, 6000.2.0b12, 6000.3.0a3

Reproducible on: M1 Max MacOS 15.5 (Tested by CQA)
Not reproducible on: No other environment tested

Note: Only spritesheets that are in a resources folder give this issue; if the spritesheet is dragged out of the resources folder, everything works as expected