Fix WooCommerce chosen Shipping Method during Address/ZIP code change on Form Totals update

functions.php

<?php
add_filter('woocommerce_shipping_chosen_method', function ($default, $rates = [], $chosen_method = null) {
    $rates = $rates ? (array)$rates : [];

    if ($chosen_method and isset($rates[(string)$chosen_method])) {
        return $chosen_method;
    }

    return $default;
}, 10, 3);