lib-tribe-events.php

/**
 * Allow past events to be queried in ACF Post Object
 * Add 'custom' to query as per tribe_get_events();
 *
 * @link   https://theeventscalendar.com/knowledgebase/using-tribe_get_events/
 */
function my_relationship_query( $args, $field, $post ) {

  $args['eventDisplay'] = 'custom';

  return $args;

}

add_filter('acf/fields/post_object/query', __NAMESPACE__ . '\\my_relationship_query', 10, 3);