wp_list_categories and custom post types

Question

I'm confused.

• I have a custom post type "asset".
• I created posts, and they are all at /asset/post-title
• I assigned categories to the custom post type, e.g. "patterns"
• The categories page shows the number of posts in each category
• If you look at the post meta for any of these posts in single view, it displays the category(ies) assigned to it.

HOWEVER, it you click the category link in the post meta ("patterns"), I get a page "nothing found".

If I assign the category to a normal post type, those will show of the category page.

What did I forget?

EDIT: I should also add that the LINK for "patterns" is /category/patterns

Answer 1

By default, category archives only show posts of the default 'post' type. The below code should get it working how you want. —via CSS Tricks

function namespace_add_custom_types( $query ) {
    if( is_category() || is_tag() && empty( $query->query_vars['suppress_filters'] ) ) {
        $query->set( 'post_type', array(
            'post', 'your-custom-post-type-here'
        ));
        return $query;
    }
}
add_filter( 'pre_get_posts', 'namespace_add_custom_types' );