Steps to reproduce:

Create a project and add view3D

Open 3D Editor

Click 'File' -> 'Close all projects and editors' and save all changes

Create a new project without closing the design studio

-> 3D Editor in the new project is showing unresponsive 3D Editor from the previously closed project.

3D Editor updates if Quick3D is imported, some Qt Quick 3D item is added and refresh button is clicked.