Steps to solve any issue:
1) Get the steps to recreate the issue. In your case it's asking what products they have in cart and what is their shipping address.
2) Recreate the issue yourself so you can understand the problem.
3) Identify the problem and solve it.
To me it sounds like either the product(s) aren't attached to a shipping profile, or Priority Express is the only option you have available for the customer's location.
You can solve those in Settings > Shipping & Delivery.