Locked gate/area in Kingston remains locked -- what am I supposed to do?

[DeadByDefault]

I have done everything in Kingston -- that is to say, I have completed all main mission objectives, collected all the collectibles, synchronized all the synchronization points save the one in the locked area, and looted all the chests INCLUDING all the secrets --, and yet the locked gate/area remains locked. Now I have no idea what I am supposed to do in order to unlock the area. I watched videos on YouTube, yet I did everything those people did, and it does not help. Any ideas?

[ahmz]

You have to continue with the story missions to unlock the gate.

[DeadByDefault]

Originally posted by ahmz:

You have to continue with the story missions to unlock the gate.

Missions outside of Kingston?

[ahmz]

The main mission, wherever it is, the yellow circle with the ! - That's the main storyline.

[DeadByDefault]

All right, thank you for your time!

[Mu'Ammar of Carthus]

In other words just moronic game design.
You bust your ass infiltrating a zone, and you can't go any further because storyline.
Classic Ubisoft.