Are the clients still able to “Interact” and open it up?
The outline and text is done locally on the client in the InventoryPlayerController OnTick(). The Use is a command sent to the server and then the server checks to see if the client is allowed to open the container.
It looks like for some reason your clients aren’t running the loop that shows them when they have a target highlighted. So I would take a look at the OnTick() in the controller.