This is a typical PHP issue. JavaScript has nothing to do with it, because the request returns an empty document. Oh well. In my spare time I’ll try to fix it. Thank you for your patience 🙂
Thank you for writing.
Unfortunately, the problem still occurs. I checked and found the place where it happens:
Elements.php: $widgets_manager->register( new $this->registered_elements[ $active_element ][‘class’] );
var_dump($active_element); -> string(13) “adv-accordion”
We have exactly the same problem. There is definitely a conflict between these two plugins.