Query.php

<?php
public function add_query_args__current( $args, $atts ) {
		/*
		 * The query does not change if the current post type or the specific post is excluded.
		 */
		if ( wpmtst_assignment_is_post_excluded( get_the_ID() ) ) {
			return $args;
		}

		/*
		 * Single post or page
		 */
		if ( is_single() || is_page() ) {
			$args['meta_key']   = 'strong_assignment';
			$args['meta_value'] = get_the_ID();

			return $args;
		}

		/*
		 * Archives
		 */
		if ( ( is_post_type_archive() || is_category() || is_tax() || is_home() ) && in_the_loop() ) {
			$args['meta_key']   = 'strong_assignment';
			$args['meta_value'] = get_the_ID();

			return $args;
		}

		if ( ( is_post_type_archive() || is_category() || is_tax() || is_home() ) && ! in_the_loop() ) {
			// get the IDs of all posts being displayed
			global $posts;
			$post_list = array();
			foreach ( $posts as $post_object ) {
				$post_list[] = $post_object->ID;
			}
			$args['meta_key']     = 'strong_assignment';
			$args['meta_value']   = join( ',', $post_list );
			$args['meta_compare'] = 'IN';

			return $args;
		}

		return $args;
	}