Q: Apple Pay not surfacing automatically anymore when near a contactless payment point

Apple Pay has been working fine until a week ago. Before, it surfaced automatically when near a contactless terminal, but now nothing happens. I have to open the phone, open the passbook, and choose the credit card before I am able to make a payment. This happens at all Oyster terminals on the tube as well as at merchants, so I assume it is an issue with the phone.