After entering play mode, the assigned texture in a 2 Texture Asst field gets reset.

To repro:
- download this project
- Open the Sample Scene
- Open the shader called GR in shader graph
- assign the default-particle texture to the 2D Texture Asset
- Enter play mode
- Go back to the graph view and notice the texture has been un-assigned

Expected result: the assigned texture should be remembered. This becomes very annoying when prototyping a new shader.
Tested with 5.3.3, 5.6.2 and 6.5.2
tested in editor versions: 19.1.0b7 and 19.2.0a9