Here’s in editor:
Here’s while testing:
I am also on mac. I forgot to put that out there.
Preview appears on unbuilt static shadows, so either build your lighting or switch the light to movable.
As for why it appears in editor but not the game, iirc there’s an option to hide preview shadows in game which is enabled by default. I thought it used to hide the entire unbuilt shadow, but I could be wrong!