My test setup looks like so. A hot spotlight sits overhead. This is in an enclosed interior that, without the spotlight, is full black. Outside this interior (which is just a big 6-walled box) you’d see the usual skylight/atmosphere setup, which is all still there, I’ve just made a dark interior box.
Left is an actor made of movable meshes. Right is a (static) static mesh.
When I move the actor, the shadow doesn’t follow it. This shadow appears to be from Lumen contribution, as I don’t have any static or stationary lights in the scene, and it appears in Lumen Scene.
Now all I do is move the static mesh and- pop, the disconnected shadow updates and now things look fine again.
So yeah, bug?
It appears to be spotlight-specific. Or at least, if I remove the walls and ceiling here and disable the spotlight, so now it’s lit just by the Skylight, and I do this same experiment? It all looks the same, the same shadows are cast and the Lumen Scene looks the same, but there’s no bug. When I move the actor, the shadow simply moves immediately to wherever I placed the actor, as you’d expect.
Oh! Also, this isn’t truly permanent. If I reload UE5, the shadow will now be under the moved object. If I move the object, so now there’s a stranded shadow, and then enter PIE? The shadow will correct itself (though oddly go back to the bugged/stranded state when I leave PIE).
More distressingly though, if I drop into PIE and move the object in-game? It leaves the shadow behind. So it clearly isn’t updating (whatever this is) in remotely real-time, it’s more something that’s only updated on initial load, or moving a static mesh in-editor.