Victor

```php $labels = array( 'name' => __('Artwork'), 'singular_name' => __('Artwork'), 'add_new' => __('Add New'), 'add_new_item' => __('Add New Artwork'), 'edit' => __( 'Edit' ), 'edit_item' => __('Edit Artwork'), 'new_item' =>...

I think that the issue is related why the get_taxonomy (https://developer.wordpress.org/reference/functions/get_taxonomy/) method don't return any value in the "query_var" attribute. Then the "wp_dropdown_categories ( .." call (https://developer.wordpress.org/reference/functions/wp_dropdown_categories/) in PostTypeAdmin class,...

Ok, identified the issue. The param "query_var" when is declared in register_extended_taxonomy must be set to true.

It would be very interesting to have it

But I understand that the implementation of getting the pckecode is delegated to the inheriting class. In the GenericProvider class there is no way to be able to get this...