Because we’re setting the location on the client instead of the server, movement is only seen on the client. The server is the authority of the state, so regardless of what the client says the state is, the server’s state overrides it. Interestingly, the location of the platform on the client actually matches that of the server. If you try to jump on where the platform is visually on the client, you’ll fall through it. But if you jump on where the platform is located on the server as the client actor, you’ll end up on top of the platform on the client.
What I find super interesting (and equally confusing) is that when I jump onto the platform as my server’s actor, the server’s actor’s location is updated on the client’s side, even though the actor on the server (authority) isn’t moving. My guess as to why this happens is because there’s some other property on the platform that the server automatically replicates in the background (e.g. bIsStandingOn). Otherwise, I would expect that the client’s actor would be floating in air.