I've tried recreating the grabbing multiple unconnected parts without the loss of connection nodes but it seems impossible. The loss of connection nodes often indicates that the multi-part grab is present. I did notice that when I tried to undo removing the parts the game acted as though every part on the rocket was disconnected and then reconnected and that the connection node would reappear if I only hit undo once and I had only grabbed one part. if multiple parts were pulled off hitting undo would not cause the connection nodes to reappear.