function llms_update_3160_ensure_no_lesson_dupe_rels() {

	if ( 'complete' !== get_transient( 'llms_update_3160_ensure_no_dupe_question_rels_status' ) ) {
		return true;
	}

	$skip = get_transient( 'llms_3160_skipper_dupe_l' );
	if ( ! $skip ) {
		$skip = 0;
	}
	set_transient( 'llms_3160_skipper_dupe_l', $skip + 100, DAY_IN_SECONDS );

	global $wpdb;
	$res = $wpdb->get_results(
		$wpdb->prepare(
			"SELECT post_id AS lesson_id, meta_value AS quiz_id
		 FROM {$wpdb->postmeta}
		 WHERE meta_key = '_llms_quiz'
		   AND meta_value != 0
		 ORDER BY lesson_id ASC
		 LIMIT %d, 100
		;",
			$skip
		)
	); // db call ok; no-cache ok.

	if ( ! $res ) {
		set_transient( 'llms_update_3160_ensure_no_lesson_dupe_rels', 'complete', DAY_IN_SECONDS );
		return false;
	}

	$quizzes_set = array();

	foreach ( $res as $data ) {

		$lesson = llms_get_post( $data->lesson_id );
		if ( ! $lesson ) {
			continue;
		}

		// Quiz no longer exists, unset the data from the lesson.
		$quiz = llms_get_post( $data->quiz_id );
		if ( ! $quiz ) {
			$lesson->set( 'quiz', 0 );
			$lesson->set( 'quiz_enabled', 'no' );
			continue;
		}

		/**
		 * Quiz already attached to a lesson
		 * + duplicate it
		 * + assign lesson/quiz relationships off new quiz
		 * + find quiz attempts by old quiz / lesson
		 * + update attempt quiz id
		 * + update attempt question ids
		 */
		if ( in_array( $data->quiz_id, $quizzes_set ) ) {

			$orig_questions = get_post_meta( $data->quiz_id, '_llms_questions', true );
			$qid_map        = array();
			$dupe_quiz_id   = llms_update_util_post_duplicator( $data->quiz_id );
			foreach ( $orig_questions as &$oqdata ) {
				$dupe_q                   = llms_update_util_post_duplicator( $oqdata['id'] );
				$qid_map[ $oqdata['id'] ] = $dupe_q;
				$oqdata['id']             = $dupe_q;
			}
			update_post_meta( $dupe_quiz_id, '_llms_questions', $orig_questions );
			update_post_meta( $dupe_quiz_id, '_llms_lesson_id', $data->lesson_id );

			$lesson->set( 'quiz', $dupe_quiz_id );

			// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
			$attempt_ids = $wpdb->get_col(
				"
				SELECT id
				FROM {$wpdb->prefix}lifterlms_quiz_attempts
				WHERE quiz_id = {$data->quiz_id} AND lesson_id = {$data->lesson_id}"
			); // db call ok; no-cache ok.
			// phpcs:enable WordPress.DB.PreparedSQL.InterpolatedNotPrepared

			foreach ( $attempt_ids as $aid ) {
				$attempt   = new LLMS_Quiz_Attempt( $aid );
				$questions = $attempt->get_questions();
				foreach ( $questions as &$aqd ) {

					if ( isset( $qid_map[ $aqd['id'] ] ) ) {
						$aqd['id'] = $qid_map[ $aqd['id'] ];
					}
				}
				$attempt->set_questions( $questions, true );
				$attempt->set( 'quiz_id', $dupe_quiz_id );
				$attempt->save();

			}
		}

		$quizzes_set[] = $data->quiz_id;
		$lesson->set( 'quiz_enabled', 'yes' ); // Ensure the new quiz enabled key is set.

	}

	// Run it again.
	return true;

}