I am using 4.16 right now and I have an inventory system. (like most it has a drop system) The drop system spawns the actor (the item) and if it is in multi player only the client can see it, Not the server nor other clients can see it.
Here is the setup I have for dropping the item.
And this is not only for the items, any actor that a player spawns in can only be seen by the client that spawned the actor. this problem I have can also be found in the First Person Shooter Template that unreal engine comes with. the spawned projectiles are only seen by the client that spawned them. If there is a fix pleas let me know because that would really help for multiplayer!
~Thanks in advance!