How to reproduce:
1. Create a new project with the “3D Core” template
2. Add the latest Entities Package (Window > Package Manager > Unity Registry)
3. Create a new Sub Scene (right-click in Hierarchy > New Sub Scene > Empty Scene)
4. Add a Cube GameObject to the Sub Scene (right-click on “New Sub Scene” > GameObject > 3D Object > Cube)
5. Save the Scene then Build And Run
6. Observe Player

Expected result: the “Cube” GameObject is visible
Actual result: the “Cube” GameObject is not visible

Reproduced with: 1.0.8, 1.0.11 (2022.3.3f1)

Reproduced on: Windows 10 (by reporter), Windows 11

Notes:
1. The “Main Camera” GameObject’s camera preview renders the “Cube” GameObject
2. The “Cube” GameObject is not visible in Play Mode or Game view
3. Reproducible with Standalone, Android, and WebGL platforms
4. Reproducible with “3D Core”, and “3D (URP)” templates
5. Reproducible with “3D (HDRP)” template, but the “Main Camera” GameObject’s camera preview does not render the “Cube” GameObject