Did you uninstall the fast checkout extension? Please check for any JavaScript errors in the browser console or errors in the AbanteCart error log.
1. how to be sure if fast checkout uninstalled?
2. the browser console showing next error: (Pattern attribute value ^(\+\d{1,2}\s)?\(?\d{3}\)?[\s.-]\d{3}[\s.-]\d{4}$ is not a valid regular expression: Uncaught SyntaxError: Failed to execute 'checkValidity' on 'HTMLFormElement': Invalid regular expression: /^(\+\d{1,2}\s)?\(?\d{3}\)?[\s.-]\d{3}[\s.-]\d{4}$/v: Invalid character in character class)
i replaced the Phone Validation Regex Pattern: on Admin/Settings/Checkout with: ^\+?(\d{1,3})?[-.●\s]?(\(?\d{1,4}\)?)[-.●\s]?(\d{1,4})[-.●\s]?(\d{1,9})$
3. i discovered that the address book repeating same address information in a new operation so we get many and many same repeated address in the AddressBook.
Why? i deleted the repeated address but again they been generated automatically as you can see in the screenshot.
4. the phone number format cannot be edited as should be and always giving an error.