It's appeal or pay, reps have been made and rejected.
So, entering and stopping within the box is accepted. The next issue is, why?
It's clear that the order of events could not have been that the vehicle ahead stopped for the lights then you stopped behind them, there isn't room.
So, IMO the only scenarios are that you stopped for the lights or that the lights are a red or green herring and in fact you stopped because you were prevented by the vehicle ahead which had stopped for its own reasons beyond the lights.
IMO, there isn't definitive evidence one way or the other so it's about accumulating circumstantial evidence. Was the woman on the footway heading to the crossing, would the lights have changed so promptly(these are pedestrian-activated and so have a default green phase)? Unfortunately, the road ahead of your vehicle can't be seen again until well after you stopped. Given the period you were stationary, if you'd stopped because the vehicle ahead was stationary then you would have set off together and we might have seen it which would undermine your argument. If for the lights then we'd expect to see a clear road immediately ahead. Sadly, we don't see the road ahead.
Balance of probabilities - your cab stopped short of the crossing. Likelihood that this was coincidentally a few feet behind the stationary vehicle ahead v you stopped there because it's where a vehicle stopping for someone on the crossing would stop. Another factor is the phasing of the lights. If you were stopped there but the vehicle ahead wasn't then they went from red to green to red in the time you were stationary, 14 seconds est. It's plausible.
Just some thoughts.