The other assumed scenario includes the statement : “In this case the ice might then travel and be ‘caught’ in the pipework, spar valve, LP pump inlet or on the face of the FOHE, thereby causing a restriction to the fuel flow” but fails to state how this could have happened so close together in two separate systems and to almost exactly the same degree (1.06 versus 1.07).
As far as I understand, fluid dynamics is a field where science has not yet reached even close to the near-100% understanding that we have about mechanics, to name one example. Remember chaos theory: a minute difference in the input conditions can cause huge differences in the result. Maybe the sun had warmed the left (south) engine 0.049 degrees more, requiring an additional chunk of ice before the left engine's fuel flow was restricted. We just don't know yet. But I've seen enough strange ice and slush formations in nature to appreciate that it's not a simple thing to research.