wp_list_categories to display CPT categories

Have you flushed your permalink rules since making the post types?

Curious if the custom post type isn’t being listed as part of the category archive.

Try out my reply at https://wordpress.org/support/topic/problem-with-categories-20?replies=6#post-7874667 but change out your own information and post type slug, and see if that helps resolve this.

Excellent. Thanks.