Slitherine

I have gotten all the way to Brisbane and broke through 3 the defensive lines I need to win as per the Primary Objectives page but its not being counted as captured and preventing scenario to be won...?

You know, of course, that you must also take the U.S. HQ to win the scenario. That said, I would wager that you did indeed take all of the 3 defensive perimeter VPs but this one is not registering because the trigger is pointing to a hex which is two hexes away from the VP itself:
Most of the time, the player would probably run over that hex anyway, just before or soon after taking that VP - that would explain why nobody has ever complained about this as far as I can tell. However, perhaps you have not taken that hex yet?

In any event, it is a bug and thank you for reporting it. I have moved this thread to Tech Support while leaving a mirror copy of it here in the main forum where you originally posted.