EntitySubqueue save() only working with die() following it

I am trying to add an item to a sub-queue automatically on save. And for some reason, it only works if I include die() afterwards.

This adds the new node to the queue

function custom_module_entity_insert(EntityInterface $entity) {
  ...
  $subqueue = EntitySubqueue::load($entityqueue_id);
  $subqueue->addItem($entity)->save();
  die();
}

This does NOT add the new node to the queue

function custom_module_entity_insert(EntityInterface $entity) {
  ...
  $subqueue = EntitySubqueue::load($entityqueue_id);
  $subqueue->addItem($entity)->save();
}

I've tried putting sleep statements around and can't get it to work without die(), which breaks the page after saving, obviously. There aren't any helpful messages in the error log. The item saves, it just doesn't get added to the queue without die().

Do you have any idea?

This is my working function (and breaks the page)

/**
 * Implements hook_entity_insert().
 */
function custom_module_entity_insert(EntityInterface $entity) {
  // Only worry about entities that are fieldable.
  if ($entity instanceof FieldableEntityInterface) {
    if ($entity instanceof NodeInterface &&
        in_array($entity->getType(), ['podcast','video','post'])) {
      automaticallyAddToEntityqueue($entity);
    }
  }
}

function automaticallyAddToEntityqueue(EntityInterface $entity) {
  $entity_queue_type_mapping = array(
    'podcast' => 'everything_else_podcast',
    'video' => 'everything_else_video',
    'post' => 'everything_else_post'
  );
  foreach ($entity_queue_type_mapping as $type => $entityqueue_id) {
    if ($entity instanceof NodeInterface && $type == $entity->getType()) {
      /** @var \Drupal\entityqueue\EntitySubqueueInterface $subqueue */
      $subqueue = EntitySubqueue::load($entityqueue_id);
      if (method_exists($subqueue, 'addItem')) {
        $subqueue->addItem($entity)->save();
        die();
      }
    }
  }
}