View filters on rh_action with null values in database

This may be helpful to someone - we wrote an update hook to batch update records that had null values:

/**
 * Rabbit Hole update to default for NULL values for nodes.
 */
function MY_MODULE_update_10001(&$sandbox) {

  // Set array of node ids to update in sandbox.
  if (!isset($sandbox['ids'])) {
    $ids = \Drupal::entityQuery('node')
      ->accessCheck(FALSE)
      ->condition('rh_action', NULL, 'IS NULL')
      ->sort('nid')
      ->execute();
    $sandbox['ids'] = $ids;
    $sandbox['current'] = 0;
    if (empty($sandbox['ids'])) {
      $sandbox['#finished'] = 1;
      return;
    }
  }

  // Set batch size.
  $items_per_batch = 100;
  // Grab the working set based off of current position and range.
  $ids = array_slice($sandbox['ids'], $sandbox['current'], $items_per_batch);

  // Exit out if nothing to do.
  if (empty($ids)) {
    $sandbox['#finished'] = 1;
    return;
  }

  // Loop over node ids.
  foreach ($ids as $id) {
    $node = \Drupal::entityTypeManager()->getStorage('node')->load($id);
    // Set default values for NULL fields.
    $node->set('rh_action', 'bundle_default')
      ->set('rh_redirect_response', 301)
      ->set('rh_redirect_fallback_action', 'bundle_default');
    $node->save();
    $sandbox['current']++;
  }

  // Set the return message - either in progress or finished.
  if ($sandbox['current'] >= count($sandbox['ids'])) {
    $sandbox['#finished'] = 1;
    $message = 'Batch update for missing Rabbit Hole values completed';
    $args = [];
  }
  else {
    $sandbox['#finished'] = ($sandbox['current'] / count($sandbox['ids']));
    $message = 'Progress: @count / @total';
    $args = [
      '@count' => $sandbox['current'],
      '@total' => count($sandbox['ids']),
    ];
  }

  // Return with message - will show progress of batch.
  return new \Drupal\Core\StringTranslation\TranslatableMarkup($message, $args);

}

Sorry I don't currently have a site with Rabbit Hole v2 on it atm. Ticket will need work for that branch and testing. thanks!