If the Shader Graph window is closed and you open a Shader Graph asset with the Return key, the Editor Window will appear blank. Note that you can work around this by docking the window, which causes the Graph to start displaying correctly.

1. Install Unity
2. Open the attached project
3. In the Project View, select the TestGraph asset
4. Press the Return key on the keyboard to open the asset

Expected Result:
The Shader Graph window opens successfully and displays the Graph correctly.

Actual Result:
The Editor Window appears mostly blank save for a few buttons at the top left.

Occurs on:
2019.1.0a9 with Shader Graph version 5.0.0-preview and LWRP version 5.0.0-preview

Does not occur on:
2018.3.0ab10 with Shader Graph version 4.1.0-preview and LWRP version 4.1.0-preview

Tested on Windows.