I seemingly can't continue the main zone/DC questline in Bangkorai. I'm not sure if it's that the questline has bugged somehow for me or whether I simply can't find the quest giver for the next quest I need.

According to my achievement progress for End of Empire, I still need to complete the last point, which is to help Emeric defeat the imperials at the Hall of Heroes.
It's need quite some time since I've been in Bangkorai though, so I've no idea how to access the Hall of Heroes. I know at some point the questline takes the player to Hallin's Stand and I've already done the quests to free the city and drive out the Imperials there, so any main quests in the city should be available when necessary.

The last place I remember visiting in regards to the main quest though is Bangkorai Garrison, which I have already reclaimed and complete (it's marked as white not black on the map), though there's a room going into the Garrison up the top which when I go to enter the game says "You do not meet the requirements." There's also the Royal Crypt, which I also cannot enter and the characters you meet throughout the questline are still in the Garrison's grounds as well.

Any and all help with this would be much appreciated.