when dragging it into the viewport it is part of the base level so it isnt spawned at all in a sense, its built with the level so it exists to all players. replication only affects things that happen after the start of the game so if somethings in the level before the game starts everyone can see it, but if its spawned into the world after the beginning of the game only the one who spawned it can see it, until that person tells everyone else about it that is. thats where the server has an advantage as it can communicate with all clients, whereas the clients can only communicate with the server and not each other.