Hi @mushroomDEW,
It appears, yes you do have a Server RPC and a Multicast in your original screenshots. My apologies for not noticing this, I was obviously replying based on the text in your second post, that’s my bad.
Why is not working? Because you have it in a level blueprint. You need to do the RPC within something that the player owns, either the character BP or the player controller BP.
If it is replicating anyway, get rid of the multicast, you don’t need it; you just need to get the server to do whatever (scale in this case, in the RPC) and then it will replicate to all clients.
NB: What are you actually trying to do here? Level BP will execute on Client and Server anyway, so it seems you are having the client tell the server to do something it would do anyway.