So, I have it working. The issue is what I thought it was. Any replication command has to be called within a PlayerController or a PlayerPawn. It is not as clean as I had hoped but a halfway house solution is to use a Blueprint Component. This BP_Component contains all relevant functions and events. It must perform a ‘Cast_To_PlayerPawn’ or controller and pull a reference to an actor variable of what the player has clicked/hit. Then the Material ID variable is set. The ROS and Multicast Events need to push through the Mat ID and the ‘Hit’ actor variable.
So the lesson I have taken away from this. All two way replication events should be contained within a Pawn or Controller. I wish the documentation made more of a statement about this. Maybe I just missed that part.