Anyone else had an issue with the game locking up when completing the above mission? When I quit out of it and reloaded, I found all areas showing "Success" but no new missions available.

Well, that kinda sucks...you'd think they'd make it a bit more obvious that was the end, especially when there's a huge empty area not unlocked on the map!

I agree. I have a sneaking suspicion that the unused area of the map is for the dlc that you could get for preordering the game originally. it was call pirates and coves or something like that I think.