Почему не отрабатывает ajax?

<tr>
                                <td><div class="alert <?=$colorClass?>" role="alert"><p><?=$users['id']?></div></td>
                                <input type="hidden" name="form_id" value="<?=$users['id']?>">
                                <td><div class="alert <?=$colorClass?>" role="alert"><p><?=htmlspecialchars($users['delivery_adress'], ENT_QUOTES)?></p></div></td>
                                <td><div class="alert <?=$colorClass?>" role="alert"><p><?=htmlspecialchars($users['delivery_time'], ENT_QUOTES)?></p></div></td>
                                <td><div class="alert <?=$colorClass?>" role="alert"><p><?=htmlspecialchars($users['surname'], ENT_QUOTES)?> <?=htmlspecialchars($users['name'], ENT_QUOTES)?> <?=htmlspecialchars($users['second_name'], ENT_QUOTES)?></p></div></td>
                                <td><div class="alert <?=$colorClass?>" role="alert"><p><?=htmlspecialchars($users['sum'], ENT_QUOTES)?></p></div></td>
                                <td><button type="button" name="delivery_status" value="1" class="btn btn-xs btn-success mb-3" id="delivered">Отдал</button></td>
                                <td><button type="button" name="delivery_status" value="2" class="btn btn-xs btn-danger mb-3">Отказ</button></td>
                                <td><button type="button" name="delivery_status" value="3" class="btn btn-xs btn-warning mb-3" data-toggle="modal" data-target="#exampleModalLong">Перенос</button></td>
                            </tr>

<?php

require_once('db.php');

if(!empty($_POST['delivery_status']))
{
    $form_id = (int) $_POST['form_id'];
    $status = (int) $_POST['delivery_status'];
    $SQL = "UPDATE Users SET delivery_status='$status' WHERE id='$form_id'";
    $result = mysqli_query($link, $SQL);
}
?>

$('button[name="delivery_status"]').on('click', function() {
    let $btn = $(this);
    let id = $btn.closest('tr').find('input[name="form_id"]').val(); // получаем id
    // формируем данные
    let data = {
        form_data: id,
        delivery_status: $btn.val()
    };
    $.ajax({
        type: "POST",
        url: "dost.php",
        data: data
    }).done(function() {
        alert("Данные сохранены");
    });
    return false;
});