metabox upload multiple file

I have upload multiple file metabox, my problem is I need to display all files links attached to this post inside the post editor. when i upload the files it is already saved under the media but the links are not showing!! please note that in frontend form the links displayed normally!

 add_meta_box(     'file_metabox', // metabox ID     'File Upload', // title     'file_metabox_callback', // callback function     'job', // post type or post types in array     'normal', // position (normal, side, advanced)     'default' // priority (default, low, high, core) );        function file_metabox_callback($  post) {      wp_nonce_field(basename(__FILE__), 'file_metabox_nonce');          // here is my problem!!!      $  args = array(         'post_type' => 'attachment',         'post_parent' => $  post->ID     );      echo '<ul>';     foreach (get_posts($  args) as $  image) {         echo '<li><a href="' . wp_get_attachment_url($  image->ID) . '" target="_blank">' . basename(get_attached_file($  image->ID)) . '</a></li>';     }     echo '</ul>';      echo '<form method="POST" name="vendor_form" enctype="multipart/form-data">';     echo '<input class="form-control" type="file" id="file_metabox" name="file_metabox[]" multiple="multiple">';     echo '</form>'; }  function file_save_meta($  post_id, $  post) {      // nonce check     if (!isset($  _POST['_mishanonce']) || !wp_verify_nonce($  _POST['_mishanonce'], 'somerandomstr')) {         return $  post_id;     }      // check current use permissions     $  post_type = get_post_type_object($  post->post_type);      if (!current_user_can($  post_type->cap->edit_post, $  post_id)) {         return $  post_id;     }      // Do not save the data if autosave     if (defined('DOING_AUTOSAVE') && DOING_AUTOSAVE) {         return $  post_id;     }      // define your own post type here     if ($  post->post_type != 'job') {         return $  post_id;     }          if ($  _FILES) {         $  files = $  _FILES["file_metabox"];         foreach ($  files['name'] as $  key => $  value) {             if ($  files['name'][$  key]) {                 $  file = array(                     'name' => $  files['name'][$  key],                     'type' => $  files['type'][$  key],                     'tmp_name' => $  files['tmp_name'][$  key],                     'error' => $  files['error'][$  key],                     'size' => $  files['size'][$  key]                 );                 $  _FILES = array("file_metabox" => $  file);                 foreach ($  _FILES as $  file => $  array) {                     // $  newupload = frontend_handle_attachment( $  file, $  post_success );                     if ($  _FILES[$  file]['error'] !== UPLOAD_ERR_OK) __return_false();                      require_once(ABSPATH . "wp-admin" . '/includes/image.php');                     require_once(ABSPATH . "wp-admin" . '/includes/file.php');                     require_once(ABSPATH . "wp-admin" . '/includes/media.php');                      $  attach_id = media_handle_upload($  file, $  post_success);                                           add_post_meta($  post_id, 'file_metabox', $  attach_id);                     update_post_meta($  post_id, 'file_metabox', $  attach_id);                 }                 return $  attach_id;             }         }     }      return $  post_id; }   

and here is the function of the frontend form which is working perfectly!

add_action('init', 'vendor_new_post');  function vendor_new_post($  post_id) {      if (isset($  _POST['submit_seo']) || isset($  _POST['vendor_file_flag'])) {           $  first_name = sanitize_text_field($  _POST['submitted_first_name']);         $  seo_title = sanitize_text_field($  _POST['submitted_seo_title']);         $  seo_robots = sanitize_text_field($  _POST['submitted_seo_robots']);          $  vendor_post = array(             'post_type' => 'job',             'post_title' => $  first_name,             'post_status' => 'publish',             'meta_input' => array(                 'first_name' => $  first_name,                 'seo_title' => $  seo_title,                 'seo_robots' => $  seo_robots              )         );          $  post_success = wp_insert_post($  vendor_post);         update_post_meta($  post_id, 'file_metabox_callback', $  post_success);          if ($  _FILES) {             $  files = $  _FILES["vendor_file"];             foreach ($  files['name'] as $  key => $  value) {                 if ($  files['name'][$  key]) {                     $  file = array(                         'name' => $  files['name'][$  key],                         'type' => $  files['type'][$  key],                         'tmp_name' => $  files['tmp_name'][$  key],                         'error' => $  files['error'][$  key],                         'size' => $  files['size'][$  key]                     );                     $  _FILES = array("vendor_file" => $  file);                     foreach ($  _FILES as $  file => $  array) {                         // $  newupload = frontend_handle_attachment( $  file, $  post_success );                         if ($  _FILES[$  file]['error'] !== UPLOAD_ERR_OK) __return_false();                          require_once(ABSPATH . "wp-admin" . '/includes/image.php');                         require_once(ABSPATH . "wp-admin" . '/includes/file.php');                         require_once(ABSPATH . "wp-admin" . '/includes/media.php');                          $  attach_id = media_handle_upload($  file, $  post_success);                                                  update_post_meta($  post_success, 'file_metabox', $  attach_id);                     }                 }             }         }     } }