Show More button does not display if results total less than the Items to Display number

I'm facing the same exact issue, I'll try to identify the source of the bug

I've changed the pager ID to 2 in order to apply the condition in the following code:

function views_show_more_preprocess_views_show_more_pager(&$vars) {
  /** @var \Drupal\Core\Pager\PagerManagerInterface $pager_manager */
  $pager_manager = \Drupal::service('pager.manager');

  $element = $vars['element'];
  $parameters = $vars['parameters'];
  $pager = $pager_manager->getPager($element);
  if (!$pager) {
    return;
  }
  $current = $pager->getCurrentPage();
  $total = $pager->getTotalPages();
  $pager_classes = ['js-pager__items', 'pager__items', 'pager-show-more'];

  if ($current < ($total - 1)) {
    $options = [
      'query' => $pager_manager->getUpdatedParameters($parameters, $element, $current + 1),
    ];

    $vars['item'] = [
      'href' => Url::fromRoute('<none>', [], $options),
      'text' => $vars['options']['show_more_text'],
      'attributes' => [
        'title' => t('Go to next page'),
      ],
    ];
  }
  else {
    $pager_classes[] = 'pager-show-more-empty';
  }

  $vars['attributes'] = new Attribute([
    'class' => $pager_classes,
  ]);

  // This is based on the entire current query string. We need to ensure
  // cacheability is affected accordingly.
  $vars['#cache']['contexts'][] = 'url.query_args';

  $vars['heading_id'] = Html::getUniqueId('pagination-heading');
}

The reason I did this is because when printing the values of $current and ($total - 1), they would always display 0. By setting the pager ID to 2, I was able to ensure the condition works as expected.

I believe this issue will only occur when both of the following conditions are met:

1. Initial items is set to a number lower than Items to display
2. The total number of results is great than Initial items, but less than Items to display

And I believe this is a limitation of core's Pager class. Upon initialization, it calculates the total number of pages based only on the items per page, it does not consider a different initial amount visible. See: Pager:setTotalPages() which is called from the constructor.

This is a shame, I would really like to show X initially, then show all after clicking "Show more"