Originally Posted by TheMadGamer 
I'm not sure about that. At least for me. Because I had no more main quest direciton in my quest log. I had no way to sail to the final game location. I was just sort of stuck with nothing to do and despite talking to every NPC in the game, twice, could not get a new main quest going.
Are you sure you talked to
everyone? Did you try going to Antigua and talking to Admiral Alvarez again? Doing so should have updated the main quest, but if not, then yeah, it was definitely bugged.