Steps to reproduce:

1. Create a new project
2. Create a new material in the Assets/ folder in the Project window
3. Select the material and navigate to the Inspector (make sure visual preview is brought up)
4. In the preview section, click on the "Shape" button next to the "Play" button to change the material preview model

Expected result: the material is previewed on selected 3D models

Actual result: the 3D model does not change

Reproduces on: 2023.3.0a8 (trunk)

Does not reproduce on: 2023.1.3f1
h2. Preliminary investigation results

There are multiple instances of MaterialEditor that get created and the button event seem to be forwarded to a leaked instance.

• This bug doesn't occur when using the "Properties" view (`Right-Click a material > Properties...` towards the bottom of the menu).
• This bug doesn't occur if the first inspector after a domain reload is a material inspector. Any other inspection afterward will have the bug.
• De-selecting and re-selecting the material will show the updated preview mesh (as expected because we are reading it from editor prefs on awake)
• I've verified that the instance ID of the `MaterialEditor` that receives `OnSelectedMeshClick` is not the same as the MaterialEditor rendering the preview in `DoRenderPreview`
• The same bug occurs with the light mode button (next to the preview mesh button). It's safe to assume that the whole toolbar is non-functional.