Empty Resource metadata property disappears from inspector when reopening the scene

### Tested versions

- Tested and confirmed on: v4.0.4, v4.2.2, v4.3 and v4.4-dev2.
- v3.6 did not have metadata in the inspector to test.

### System information

Windows 10 - Godot v4.3.0-stable

### Issue description

After creating a metadata property of type Resource and reopening the scene, the editor inspector does not show the property, even though it still exists in the scene's tscn file.

The property should still be visible, even if there is no value set.

### Steps to reproduce

1) Create a scene and add a metadata property of type Resource.
2) Do not add any value to it and save the scene.
3) Close and reopen the scene.

### Minimal reproduction project (MRP)

[Metadata Test.zip](https://github.com/user-attachments/files/17175944/Metadata.Test.zip)
It may not show, but the scene already has a metadata of type resource.