UE5 Material Instance Preview Bug

Hi, all.

I’m currently having rendering issues.
I’m using the UE5 editor under development by building it from source code.

It presents the correct display in the preview inside the material’s node editor.
However, when I create the instance of that material, the generated one looks strange.

The part that should work as reflection becomes black.

If the material node itself is wrong in the first place, the preview in the material editor should also be wrong.

Why does the material instance behave differently ?

Similar bugs have been reported.