RXJS observable in observable

I made this code:

return this.projectService.oneById(id).pipe(mergeMap(project => {
      if (!project) {
        return [];
      }

      const stories = this.getStories(id);

      return combineLatest(project.members.map(member => {
        return this.userService.one(member.id).pipe(map(memberData => {
          const assigned = stories.pipe(mergeMap(t => combineLatest(t.filter(task => {
            if (task && task.assignee?.id === member.id) {
              return {
                ...task,
                id: task.id
              };
            }
          }))));

          return {
            id: member.id,
            name: memberData?.displayName ?? 'Unknown',
            assigned
          };
        }));
      }));
    }));

But I'm having a problem because my function expects to return Observable<Type[]>, but it is currently returning Observable<{ ...etc, object: Observable<Type[]> }.

Obviously the problem is the observable inside the observable. I am, however, unsure how to fix this in this case. I have solved this many times in my current code, but this one is hard for me to understand because whatever I try nothing changes.

Thank you for helping in advance.

PS: the exact warning is this:

Type 'Observable<{ id: string; name: string; assigned: Observable<[UserStory | undefined]>; }[]>' is not assignable to type 'Observable<Member[]>'.   Type '{ id: string; name: string; assigned: Observable<[UserStory | undefined]>; }[]' is not assignable to type 'Member[]'.     Type '{ id: string; name: string; assigned: Observable<[UserStory | undefined]>; }' is not assignable to type 'Member'.       Types of property 'assigned' are incompatible.         Type 'Observable<[UserStory | undefined]>' is missing the following properties from type 'UserStory[]': length, pop, push, concat, and 25 more.