This is happening to me on 4.18.3 in blueprints
It happens when I set the visibility of a component on a character, specifically my overhead chat widget. When I multicast to all, then run a server RPC and use rep notify to set the chat component to visible for 10 seconds, all characters all over the world see the chat component for 2 or 3 seconds before it disappears, while those nearby see it for the full 10 seconds.