I have dragged a cube into the world, and then added an ActorComponent with just one replicated bool in it, the ActorComponent is set to replicate also.
In begin play, the server sets the replicated bool to true, but the client always sees false.
I just made a class that derives from UStaticMeshActor, and after setting its replicate option to true, everything works.
It seems placed meshes just don’t replicate when they’re converted in the editor.