[2021] Can’t progress main story in The Siege of Paris

Began The Siege of Paris when it came out, I started the quest “Sister of Sorrow” and assassinated little Mother and then nothing happened after. I have reloaded on older save, reinstalled the game and nothing. When I went back to Aquila I could not open the door and enter where little mother was holding the queen. I can’t progress the main story and have nearly 200 hours of playing time and don’t wanna start all over again.