Моя PHP-форма ничего не возвращает из $_POST

У меня относительно простая форма PHP. Когда я использую print_r($_POST);, я ничего не получаю взамен. Только этот результат:

`Array
  (
  )
  1`

Моя форма довольно проста:

<form action = "" method = "post" enctype = "multipart/form-data" class = "zip-<?php echo $atts['class']; ?>">
        <div class = "row ">
            <div class = "<?php echo $column1; ?>" <?php echo $inlineStyle ?>>
                <div class = "lds-facebook hide"><div></div><div></div><div></div><div></div><div></div></div>
                <input type = "text" name = "zip" class = "zip">
            </div>
            <div class = "<?php echo $column2 ?>">
                <button type = "submit" class = "submit" name = "submit">
                  <?php echo $buttonValue; ?>
                  <i class='fa fa-caret-right' aria-hidden='true'></i>
                </button>
            </div>
        </div>
    </form>

Цель формы — просто опубликовать, а затем перенаправить на страницу в зависимости от значения, полученного на входе. Есть предположения?

public static function find_zip_widget( $atts, $content = null ) { 
    ini_set('display_errors', '1');

    extract(shortcode_atts(array(
    'class' => 'class'
), $atts));

    // Set classes for rows
    if ($atts['class'] == 'home'){
        $column1 = 'col-md-6 col-12 my-auto text-center border-underline';
        $column2 = 'col-md-6 col-12';
        $buttonValue = 'FIND HELP RIGHT NOW';
        $inlineStyle = '';
    }

    if ($atts['class'] == 'widget'){
        $column1 = 'col-md-5 col-5 offset-2 offset-md-0 my-auto';
        $column2 = 'col-md-7 col-5 my-auto';
        $buttonValue = 'SUBMIT';
        $inlineStyle = 'style = "border-bottom: 3px solid #9EA2A4 !important;min-height: 30px;"';
    }

    ?>
    <form action = "" method = "post" enctype = "multipart/form-data" class = "zip-<?php echo $atts['class']; ?>">
        <div class = "row ">
            <div class = "<?php echo $column1; ?>" <?php echo $inlineStyle ?>>
                <div class = "lds-facebook hide"><div></div><div></div><div></div><div></div><div></div></div>
                <input type = "text" name = "zip" class = "zip">
            </div>
            <div class = "<?php echo $column2 ?>">
                <button type = "submit" class = "submit" name = "submit">
                  <?php echo $buttonValue; ?>
                  <i class='fa fa-caret-right' aria-hidden='true'></i>
                </button>
            </div>
        </div>
    </form>

    <?php    
        echo "<pre>";
        echo "Before if: ";
        echo  print_r($_POST); 
        echo "</pre>";
    ?>

    <?php 
        $states = get_categories( array(
        'orderby' => 'name',
        'order'   => 'ASC',
        'hide_empty' => false,
        'taxonomy' => 'endeavors_location_state'
        ) );


        if (isset($_POST['submit'])) {
            $postalZip = $_POST["zip"];

            echo "<pre>";
            echo "After if: ";
            echo  print_r($_POST);
            echo "</pre>";

            echo '<br> <br> PostalZip: ' . $postalZip;

            ///REDIRECT FOR CITY, STATE, or other/////
            $ch = curl_init(); 
            curl_setopt($ch, CURLOPT_URL, "https://maps.googleapis.com/maps/api/geocode/json?address='.$postalZip.'&key=AIzaSyBX_0qZmGBtiHrZMcjZfv6yL7NAbLiwnjc");
            // curl_setopt($ch, CURLOPT_URL, "https://maps.googleapis.com/maps/api/geocode/json?address=78210&key=AIzaSyBX_0qZmGBtiHrZMcjZfv6yL7NAbLiwnjc");
            curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
            $output = curl_exec($ch);

            curl_close($ch);
            $jsonResults = json_decode($output, true);



            $cityName = $jsonResults['results'][0]['address_components'][1]['long_name'];
            $stateName = $jsonResults['results'][0]['address_components'][3]['long_name'];


            $cityName = strtolower(str_replace(" ","-",$cityName));
            $stateName = strtolower(str_replace(" ","-",$stateName));

            $args = array(
                'post_type' => 'endeavors_locations',
                'post_status' => 'publish',
              'numberposts' => -1
            );

            $cityFound = 0;
            $allCityLocations = get_posts( $args );
            foreach ($allCityLocations as $location) {
                $eachCity = strtolower(str_replace(" ","-",$location->post_name));
                echo $eachCity;

                if ($location->post_name === $cityName) {
                    $cityFound = 1;
                    echo $cityFound;
                }
            }

            if ($cityFound === 1) {
                wp_safe_redirect('/locations/'.$cityName);
                } else {
                foreach ($states as $state) {
                    if ($state->slug === $stateName) {
                         $stateFound = 1;
                    }
                }
                if ($stateFound === 1) {
                wp_safe_redirect('/state/'.$stateName);
                } else {
                    wp_safe_redirect('/all-locations/');
                }
            }
        }
    ///END OF REDIRECT FOR CITY, STATE, or other/////
    } //end function