how to view 3D viewport material preview with background? I'm in the shading layout, looking at the 3D viewport. I switch to preview material mode, and turn off Lighting->Scene World. The background shows only a lightly gradiented multi tone color. Is there a key to change this to display the hdri background?
There's a simple workaround.
Put a plane with Glass BSDF material in the background and the HDRi will show.

No need to adjust or enable anything. It just works.