My Customized Submit Sort AJAX Question is Returning no posts – why?

Once I run this question on posts_type => "posts" it really works simply effective. However once I add my customized put up sort ‘post_type’ => ‘case-studies’, I get no outcomes.

The customized put up sort has a customized taxonomy arrange of ‘case_study_categories’. Can anybody spot what’s improper? I have been taking a look at this for 3 hours and simply do not perceive why it is not working.

filter-posts.php:

<?php

perform ajax_filter_posts_scripts() {
  // Enqueue script
  wp_enqueue_script('afp_script', get_template_directory_uri() . '/js/ajax/filter-posts.js', array('jquery'), null, false);

  wp_localize_script( 'afp_script', 'afp_vars', array(
        'afp_nonce' => wp_create_nonce( 'afp_nonce' ), // Create nonce which we later will use to confirm AJAX request
        'afp_ajax_url' => admin_url( 'admin-ajax.php' ),
      )
  );
}
add_action('wp_enqueue_scripts', 'ajax_filter_posts_scripts', 100);

// Script for getting posts
perform ajax_filter_get_posts() {

  // Confirm nonce
  if( !isset( $_POST['afp_nonce'] ) || !wp_verify_nonce( $_POST['afp_nonce'], 'afp_nonce' ) )
    die('Permission denied');

  $knowledge = $_POST['data'];
  $taxonomy = $knowledge['taxonomy'];
  $posts_per_page = $knowledge['posts_per_page'];

    $args = array(
    'post_type' => 'case-studies',
    'posts_per_page' => $posts_per_page,
);

  // If taxonomy will not be set, take away key from array and get all posts
  if( $taxonomy ) {
    $args['category_name'] = $taxonomy;
  }

  $question = new WP_Query( $args );
  $max = $query->max_num_pages;?>

  <?php if ( $query->have_posts() ) :

    // Used to rely the posts and evaluate to max to cover and present load extra button;
    $index = 1;

    whereas ( $query->have_posts() ) : $query->the_post();
      $index++;
      $featured_img_url_medium = get_the_post_thumbnail_url(get_the_ID(),'medium_large');
      $id = get_the_ID();
      $class = get_the_category();
      $category_name = $class[0]->cat_name;?>
      <a href="<?= get_permalink(); ?>" title="Read - <?php the_title(); ?>" class="dynamic-blogs__card card">
        <div class="news-image-container">
          <div class="hover-read-more">
            <div class="text">
              <i class="fal fa-chevron-circle-right"></i>
              <p>Learn Now</p>
            </div>
          </div>
          <img class="card-image lazy" src="<?= $featured_img_url_medium; ?>" alt="<?php the_title(); ?>" loading="lazy">
        </div>

        <div class="card-text-container">
          <?php if( $category_name ) {
            echo '<p class="card-category">' . $category_name . '</p>';
          } ?>
          <?= the_title('<h3 class="">', '</h3>'); ?>
        </div>
      </a><!-- Card END -->

    <?php endwhile; ?>
    <?php if($index <= $max ): ?>
      <div class="dynamic-blogs__load-more py">
        <div class="btn -ghost js-tax-filter" quantity="12">Load Extra</div>
      </div>
    <?php endif;  ?>
  <?php else: ?>
    <h2>No posts discovered</h2>
  <?php endif;

  die();
}

add_action('wp_ajax_filter_posts', 'ajax_filter_get_posts');
add_action('wp_ajax_nopriv_filter_posts', 'ajax_filter_get_posts');

?>