ViewportTextures do not work at runtime when applied to a material override of an instanced mesh

[depressedtimbit]

Godot version

4.0.3.stable

System information

Windows 11 - Vulkan Forward+ - GeForce GTX 1650 SUPER

Issue description

when applying material overrides/overlays to a mesh that is an instanced scene, ViewportTextures will function while in editor

but not when ran

Steps to reproduce

• start with a basic scene containing a Camera3D, SubViewport, and control nodes as children of the SubViewport
• Create a MeshInstance3D, add a mesh, Save branch as new scene
• add new material in any available slot, mesh/material, material_override, material_overlay surface_material_override
• make local to scene, add ViewportTexture assigned to the SubViewport
• at this point the material will appear as normal
• play the scene

Minimal reproduction project

N/A

[arkology]

@clayjohn this is related to what I wrote yesterday #78285 (comment) (but my case is 2d and still no MRP ATM). Please take a look
UPD: Wait, 4.0.3? No, sorry, I'm completely wrong

[Rindbee]

A duplicate of #77678. Related to #74331.