Empty Resource metadata property disappears from inspector when reopening the scene

[WagnerGFX]

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 It may not show, but the scene already has a metadata of type resource.

[dustdfg]

Can reproduce it too and it is definitely a bug

[dustdfg]

https://github.com/user-attachments/assets/16fa863a-c798-43ea-86c9-6606fdc4e168

Hello @AThousandShips! It needs bug and maybe topic:editor (and maybe topic:core I am not sure about it)

[AThousandShips]

Please don't tag random maintainers someone will get to this we are under a lot of pressure right now and I'm not working on triage today

[dlameter]

I was able to reproduce using the provided MRP, and adding my own metadata of the Resource type. Adding a value to the Resource metadata does make the value persist correctly.

System information: Godot v4.4.1.stable (4d7c448a0) - Ubuntu 24.04.2 LTS 24.04 on X11 - X11 display driver, Multi-window, 1 monitor - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1080 (nvidia; 550.120) - Intel(R) Core(TM) i7-7700K CPU @ 4.20GHz (8 threads)

cc: @AThousandShips