Steps to reproduce:

1. Create a new Unity project using a 3D Universal Template
2. Create and open a URP Lit Shader Graph
3. Under Fragment, find the Base Color property
4. Click on the color field connected to it (to open the color picker)
5. Move the color sliders to change color
6. Observe the rectangle at the top, above all color sliders

Actual results: The rectangle only shows transparency and does not change color

Expected results: The rectangle shows the old color and a newly selected color

Reproducible with versions: 2023.1.0b1, 6000.0.65f1, 6000.3.3f1, 6000.4.0b3, 6000.5.0a4

Tested on (OS): Windows 11, macOS 26.1 (M1 Pro)

{}Notes:{}{}{}

• I believe this is caused by that specific color picker window not containing an Alpha channel slider (all other found sliders in Editor contain it). Not sure if this is intentional, but if so, the alpha slider should be at 255 by default 
• Selecting a new color with the pipette tool or from the swatches correctly showcases the newly selected color
• The color is correctly represented next to Base Color property and in the Main Preview
• This is not specific to URP Lit Shader and affects any, that have such color property (HDR Color Picker has the same behavior)