Yes, the App has been 'playing up' recently. I strongly suggest you do NOT wait until you get on board to book - you may be OK and you may not. If its really important to you ring Princess now. Their lines open at 8.00am (UK time), ring on the dot and you'll get through quick (probably to someone in the US). They can book it for you. We are on the same cruise (and are booked into the Crown Grill on the 3rd!) - hope you have a great time and happy anniversary.