2D Light and Shadow ShaderGraphs cannot be assigned to the Light2D component's Material Properties by drag and dropping the asset

Steps to reproduce:

1. Open the attached project
2. Open the SampleScene
3. Select the "Spot Light 2D object" in the Hierarch
4. Click on the Search button for Light's material Property in the Inspector window
5. Observe that shadergraph assets are listed as compatible
6. Close the search window
7. Drag and Drop the "LightMat" shadergraph asset from the Project window to try and assign it to the Light's material property

Actual results: Graph assets appear in the Field's search window, but cannot be assinged by drag and droping the shadergraph assets 

Expected results: Shadergraph assets can be assigned by drag and dropping

Reproducible with versions: 6000.7.0b1, 6000.7.0b2, 7000.0.0a1

Can’t test with versions: 6000.0.84f1, 6000.3.24f1, 6000.6.2f1, 6000.7.0a6 (Light2D and Shadow2D material properties for the 2D lights are not available)

Tested on (OS): macOS 26.6.2

Notes:

• Reproducible with Light2D and Shadow2D shadergraph types