categories won't show custom post types

hi, ive added one custom post type called “places”. it works fine, but i wanted to be able to add custom post types to categories, so i followed the instructions here:

https://www.deluxeblogtips.com/2010/07/custom-post-type-with-categories-post.html

which had me add this to my functions.php in the custom post type section:

'taxonomies' => array('category', 'post_tag') // this is IMPORTANT

so my custom post type looks like this:

add_action( 'init', 'create_post_type' );
function create_post_type() {
	register_post_type( 'pn_places',
		array(
			'labels' => array(
				'name' => __( 'Places' ),
				'singular_name' => __( 'Place' )
			),
		'menu_position' => 4,
		'public' => true,
		'has_archive' => true,
		'rewrite' => array('slug' => 'places'),
		'taxonomies' => array('category', 'post_tag') // this is IMPORTANT
		)
	);
}

which gives me the ability to select categories to include the custom post type in.

the problem is that when i look at my posts by category:

https://punknomad.com/category/destinations/unusual-monuments/

i get a “no posts found” error. ive been looking around for quite a while and haven’t been able to find anything related specifically to this problem.

does anyone out there know what i can do to solve this? thanks!