GPP / child theme / stylesheets blocked

Hi there,

I'm facing a similar issue as described here. However I'm not able to figure out why certain GP stylesheets are being blocked.

Together with the Developer of the plugin (MemberPress) we made minor progress and managed to enqueue one GP stylesheet. We added the following to the function.php

// MP courses - Enque accordion CSS on lesson pages
  add_action('mpcs_courses_footer', function() { ?>
  <script>
    let toggleBtn = document.querySelector('#toggle-btn');
    let targetElement = document.querySelector('#toggled-container');
    if(toggleBtn) {
    toggleBtn.addEventListener('click', function(e) {
      e.preventDefault();
      targetElement.classList.toggle('show-content');
    });
    }
  </script>
  <?php
  });
  
 // MP courses - Enqueue GP stylesheet
  add_action( 'wp_enqueue_scripts', 'mepr_courses_enqueues', 110 );
  function mepr_courses_enqueues() {
  if( is_singular( array( 'mpcs-lesson', 'mpcs-course' ) ) ) {
      $suffix = defined( 'SCRIPT_DEBUG' ) && SCRIPT_DEBUG ? '' : '.min';
      $dir_uri = get_template_directory_uri();
      wp_register_style('generate-style-mpcs', get_template_directory_uri() . "/assets/css/main{$suffix}.css");
      wp_enqueue_style( 'generate-style-mpcs', get_template_directory_uri() . "/assets/css/main{$suffix}.css" );
  }
  }
  add_filter('mpcs_classroom_style_handles', 
    function($allowed_handles){
        $allowed_handles[] = 'generate-style-mpcs';
    return $allowed_handles;
}
);

Any thoughts as to what might be blocking the remaining GP stylesheets? (--> side by side comparison between legacy and new site)

Thanks,
Jan