The invisible scene

Hello everyone, I have an error. I can’t change the scene or add it. When I change or add a scene, it is not in the dynamic scene tree, but it is displayed in debugging, and its child nodes are also displayed. What to do? I noticed that this only happens when I change scenes before.

first of all, how do you change scene? is it the basic SceneTree’s change_scene_to_file()? or you made your own scene changing system?