Custom Mesh is not selected and editor throws NullReferenceException in Shader Graph, refer the attached video

Steps to repro:
1. Create a new project
2. Window > Package Manager > Shader Graph > Install
3. Project window > Create > Shader > PBR Graph
4. Open "New Shader Graph" from Project Window
5. Main Preview > right-click > Custom Mesh

Actual Result:
Unable to select Custom Mesh along with NullReferenceException

Expected Result:
Custom Mesh is chosen without any exceptions

Reproducible in:
2020.1.0a17, 2020.1.0a15

Working fine in:
2020.1.0a14, 2019.3.0f3

Package version found: 7.1.6, 7.1.5, 7.1.2, 7.1.1

Environment:
Windows 10 & macOS 10.14