Dawnguard quests not starting

So i just completed the bloodline quest with Serana and refused Lord Harkon's offer, but once he teleports me back to the little boat outside the fort, the new quest won't start. I cant even find the guy that's supposed to talk to me (Forgot his name), and i did a bit of looking around online and found out that he's supposed to be fighting some vampires once i enter the fort? I already tried using a fix quest bug (Ring (and scrolls) of quest fixing it was called i think) But upon using the scrolls nothing happened. I really dont want to start a new playthrough cus it took me quite a while before starting the quest. I haven't really done a lot of quests after bringing Serana back though, so going back a few saves would also be an option if that would solve anything.

Edit: I play on Xbox X if that changes anything.

Edit 2: I suppose no one has a solution since im not really getting any replies? If there is none please let me know so i can move on, but maybe someone knows a different quest fixing mod that might work?