Custom Post Type Taxonomies -Posts not showing in Category or Tag pages

You were close with the code you posted in your comment. The issue is that you only tested for is_main_query, which will limit every query on your site to that single post type.

function wpa82763_custom_type_in_categories( $query ) {
    if ( $query->is_main_query()
    && ( $query->is_category() || $query->is_tag() ) ) {
        $query->set( 'post_type', array( 'post', 'resource' ) );
    }
}
add_action( 'pre_get_posts', 'wpa82763_custom_type_in_categories' );