So I'm playing as England/UK (Ironman) and have annexed Vlaanderen. After a while a massive rebel 350k stack of Flemish rebels appeared (from over the border I think) and started seiging my provinces (ineffectually). Eventually, the stack took London, so I caved in and accepted their demands to create Flanders.
Flanders was duly created, but the London rebel stack remains. Except now it doesn't seem to have any demands - it's just sitting their denying me my capital city (and apparently not suffering any attrition).
Is there anything I can do? Or is my ironman game borked?