I am using v3 latest version and having problem with checkout while selecting delivery. Delivery option works fine when checkout as a guest. But, it shows an error message after login and selecting a previous address. After selecting an existing address it shows: "Address 1 field is required." which is clearly indicated to manually enter address to complete the checkout. I have tried entering address manually and it works fine. I think it will be good, if you can fix this problem and let the address form or address fields, auto-fill after login or selecting an existing address like customer fields.