Updating location of the cube for just the client causes some weird behaviour… When the client pawn jumps on the location of stationary (server-side) cube they are teleported to the top of their cube which has moved away from its origin.
I think that, from the server’s perspective the client pawn is located on, and is in collision with, the cube, so it updates the clients position from apparently (from client perspective) mid-air to the top of their cube.
Not sure if it is collision or maybe something a bit more subtle…