I have the same question: After we do the expansion, it exposes the Old King's Castle, which has a 60 min timer. We collect from the Old King's Castle, and we again "search for more clues". The game took me back to the Old King's Castle when I tried to "search for more clues" using the button in the Goalbook, but the clue item also looks like the same thing we got from Cottages.
Do we just keep going to the castle every hour for clues?