How to reproduce:
1. Open the “bug-report-unity-physics-world.zip“ project
2. Open the “SampleScene“
3. Enter Play Mode
4. Open the Window > Entities > Hierarchy window
5. Set the Data Mode to “Runtime“
6. Select one of the “Child” Entity’s children in the Entities Hierarchy > EntitiesSubScene and find the Physics World Index Component in the Inspector
7. Observe the Inspector

Expected result: The value is 1
Actual result: The value is 0

Reproducible in: 1.2.0, 1.3.8 (2022.3.56f1, 6000.0.34f1, 6000.1.0b1)
Could not test in: 0.51.1-preview.21 (2021.3.47f1) (No PhysicsWorldIndex Component)

Reproduced on: Windows 11 Pro (23H2)
Not reproduced on: No other environment tested

Note: This might be a Unity Physics package bug