Metatags dont work on frontpage

Metatags always use global:frontpage as settings for front. If i edit metatags for my frontpage it has no effect.

I found the problem in metatag.module on line 1228 and beyond:

  // The front page has special consideration.
  $instance = 'global:frontpage';
  if (drupal_is_front_page() && metatag_config_is_enabled($instance)) {
    $instance = 'global:frontpage';

    // These two parts are sufficient given that the homepage is unique.
    $cid_parts = array(
      'langcode' => $GLOBALS['language_content']->language,
      'url' => $GLOBALS['base_url'] . base_path() . '<front>',
    );

    // Allow each page in a sequence to have different values.
    if (isset($_GET['page'])) {
      $cid_parts['page'] = $_GET['page'];
    }

    // Allow other modules to customize the data using
    // hook_metatag_page_cache_cid_parts_alter().
    drupal_alter('metatag_page_cache_cid_parts', $cid_parts);

    $cid = "output:{$instance}:" . hash('sha256', serialize($cid_parts));

    if ($cache = cache_get($cid, 'cache_metatag')) {
      $metatags = $cache->data;
    }
    else {
      $metatags = metatag_metatags_view($instance, array());
      cache_set($cid, $metatags, 'cache_metatag');
    }

    $page['content']['metatags'][$instance] = $metatags;
  }

  // Load any meta tags assigned via metatag_page_set_metatags(). Note: this
  // must include the necessary defaults.
  else {
    $page['content']['metatags'] += metatag_page_get_metatags();
  }

What does this if-case actually do for the frontpage?

If i change and make the if-case unused like this:

  // The front page has special consideration.
  $instance = 'global:frontpage';
  if (1==2) {

Metatags seem to work properly on frontpage...

Any ideas?