So, I got this same situation and got it fixed. There is a scene at the Kahanga Palace where you get "The Coming Storm." After talking to Aldys, you have to go there and then it replays an earlier scene where you wake up and most of the heads are at the palace talking about what to do. However, it now extends the scene because Aldys shows up. Then it gives you the quest. Then it finishes the quest. I can confirm that doing this puts the Trigger at correct place and puts you on the path Ukaizo and the rest of this part of the game.
I don't even think the game is bugged. It just seems that multiple people have accidentally done a sequence break where you have gotten access to the final mission before actually getting "the coming storm" quest that tells you to go and get access to the final mission.
This may be unique to the Principi line because the pirates are completely separate, which is why we are having this problem.
You should reply to this and discuss if this helped. Also, did you happen to do like half or more of the other faction quests before settling on the Principi? I did that and I think it contributed to the sequence break.
