Issue with custom pseudo field not appearing in field group

Hi,

I created a pseudo field to render the node title in various node view modes within field groups. This field called "mymdoule_title" is created by the following code:

/**
 * Implements hook_entity_extra_field_info().
 */
function mymodule_entity_extra_field_info() {
  $extra = array();

  foreach (NodeType::loadMultiple() as $bundle) {
    $extra['node'][$bundle->Id()]['display']['mymdoule_title'] = array(
      'label' => t('Extra title'),
      'description' => t('Display the title of the node e.g. in teaser'),
      'weight' => 100,
      'visible' => TRUE,
    );
  }

  return $extra;
}

and then it is rendered with the following code:

/**
 * Implements hook_ENTITY_TYPE_view for nodes
 *
 *  - render our pseudo fields
 */
function mymodule_node_view(array &$build, EntityInterface $entity, EntityViewDisplayInterface $display, $view_mode) {

  if ($display->getComponent('mymodule_title')) {
    $build['igb_title'] = array(
      '#type' => 'html_tag',
      '#tag' => 'h2,
      '#value' => $entity->label()
    );
  }
}

The rendering is working fine a) when this field is added to a view mode without being nested into a field group or b) when it is nested within a field group where another field is also placed which has a value. If there are other field within the field group but they are empty and therefore not rendered the pseudo field is not rendere either.

Steps to reproduce:

- add the above code to a custom module, rebuild cache
- go to any node type administration page and save a view mode with this new field directy in node/ without field group (for example admin/structure/types/manage/page/display)
- add a node of this type and view it -> you should see the node title a second time
- then go to view mode administration again and add this field to a field group
- when you view the node again the second title disappears
- then go to view mode administration again and add a second field to the field group which has a value for sure
- go to the node detail page again -> the second title is visible within the field group

I tried all this in a Drupal 7 installation with no problems - seems to be a new issue with Drupal 8.

Best,
Tobias