Please add the given code in your wplms-customizer.php file in your wplms customizer plugin :
add_action(‘template_redirect’,’subscribe_free_course_fix_modern’,999);
function subscribe_free_course_fix_modern(){
global $post;
if(!is_singular(‘course’))
return;
if(isset($_GET[‘subscribe’])){
$free = get_post_meta($post->ID,’vibe_course_free’,true);
if(vibe_validate($free)){
$user_id = get_current_user_id();
bp_course_add_user_to_course($user_id,$post->ID);
}
}
}