You probably forgot to log in with your Days of Wonder account in Ticket to Ride. Go to the Settings screen inside the Station, and push the "Login" button. Enter your Days of Wonder account credentials (the SAME one that you used in Pocket during the migration steps) and voilà! This will do the trick.
Background explanation: the iOS system does not provide any mechanism to transfer an in-app purchase from one app to another. So the only solution we found was to use our players' Days of Wonder accounts to copy this information from one app to the other.