Thanks for sharing the credentials, I checked your site and the issue was coming from the woocommerce plugin. Ideally this is a woocommerce issue that it is including select2 script on the course page which woocommerce should not include.
However this is the first time I saw this issue in a website. I have added the below code in your wplms-customizer.php file:
add_action('wp_enqueue_scripts','mywplms_dequeue_Script');
function mywplms_dequeue_Script(){
if(is_singular('course')){
global $bp;
if($bp->current_action == 'admin'){
wp_deregister_script('select2');
wp_dequeue_script('select2');
}
}
}
And this fixed the issue on your site, please check and confirm.