use_sub_threads makes the game freeze when it's set to true

[Lerpwave]

Tested versions

Reproducible on Godot 4.7.1, 4.8 dev 3

System information

Godot v4.7.1.stable - Ubuntu 22.04.5 LTS 22.04 on X11 - X11 display driver, Multi-window, 2 monitors - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 3060 Ti (nvidia; 580.173.02) - 13th Gen Intel(R) Core(TM) i5-13600KF (20 threads) - 15.42 GiB memory - PulseAudio (44100 Hz, Stereo/mono)

Issue description

In my game ResourceLoader.load_threaded_request use_sub_threads = true never worked.
The issue wasn't solved by #118185.

I'm working on a large project and I didn't manage to do a MRP.
So I tried a different approach, I searched for small demos and added a scene that is set as the main scene, it loads a choosen scene with use_sub_thread set to true.

I tried a few godot demos, many just worked but I found 2 that didn't always load with use_sub_thread:

Name	Number attempts	Number of freeze	Scene loaded (PATH)	Works if use_sub_thread = false	Also freezes on 4.8 dev 3	link
Gdquest TPS demo	30	29	res://main.tscn	Yes (30 attempts)	yes	https://github.com/gdquest-demos/godot-4-3d-third-person-controller
Godot Third-Person Shooter Demo	90	6	res://level/level.tscn	Yes (30 attempts)	yes	https://github.com/godotengine/tps-demo

The ones that had no problem:
From https://github.com/godotengine/godot-demo-projects :

name	scene
squash the creeps demo	res://Main.tscn
RigidBody Character 3D Demo	res://level.tscn
Platformer 3d demo	res://game.tscn

From https://github.com/gdquest-demos/

name	scene
New features in Godot 4 (GDQuest)	3d_physics_nodes.tscn
New features in Godot 4 (GDQuest)	3d_balls_pool.tscn
Gdquest Open Rpg	res://src/main.tscn

Steps to reproduce

1. Download the attached load.zip, and extract it on the Gdquest TPS demo or the Godot Third-Person Shooter Demo.
2. Set the main scene of the demo in the Project Settings to load.tscn.
3. Set the PATH in load.gd to respectively res://main.tscn or res://level/level.tscn
4. Launch the game until it freezes.

Minimal reproduction project (MRP)

load.zip