1. What happened
The "Entities Hierarchy" window stops displaying anything when a subscene is loaded using SceneSystem.LoadSubScene(worldUnmanaged, entitySceneReference), and the console outputs the following error:
"ArgumentException: A component with type:Unity.Scenes.SubScene has not been added to the entity."

2. How can we reproduce it using the example you attached
* Open the "MainScene"

* Make sure the "Entities Hierarchy" window is not open currently

* Press play. At this moment, a "SceneLoaderSystem" will find a "SceneLoader" entity in the "BaseSubScene", and will load another subscene that's stored as an "EntitySceneReference" in that "SceneLoader" component

* Open the "Entities Hierarchy" window

* Notice error in console and nothing is shown in window

Unity version : 2022.2b8