Editor switches to 2D view for all Subviewport controls, where they can't be seen. How to force it to stick to 3D view?

Godot Version

4.2.2.

Question

I’m displaying 2D interface items in a 3D space, and in order to do this I have a Sprite3D that points to a Subviewport, and in that Subviewport I’m laying out the Controls that I’m displaying in 3D. The scene tree looks like this:

Node3D (pivot)
/ Sprite3D (points to SubViewport)
// SubViewport
/// Panel control
//// HBox control
///// Other various controls I want to display

However, whenever I go to start editing the controls in the editor, the editor switches to 2D view - and the controls all disappear, leaving a blank editor. If I select the sprite or pivot, or if I manually switch to 3D view, the controls appear and I can edit them perfectly fine, but every time I select a new control it reverts to the 2D view again.

How can I get the editor to stop doing this and display these nodes in 3D view, where I can actually see them? Alternatively, is there a way to make them visible in the 2D view as well?