WordPress: Adding Custom Post Types to Tag/Category Results

wordpress.custom-post-types-category-in-results.php

// Adding Custom Post Types to Tag/Category Results
function add_custom_types_to_tax( $query ) {
	if( is_category() || is_tag() && empty( $query->query_vars['suppress_filters'] ) ) {

		// Get all your post types
		$post_types = get_post_types();

		$query->set( 'post_type', $post_types );
		return $query;
	}
}
add_filter( 'pre_get_posts', 'add_custom_types_to_tax' );