Reply To: pre_get_posts to get all posts connected to single object

For some reason my query is setting post type to any. For some reason in parse_query it will change the post type any when using a tax_query. I don't have a tax_query nor do I have any taxonomies on these two post types.

https://developer.wordpress.org/reference/classes/wp_query/parse_query/

Search for post_type

add_action( 'parse_query', 'rel_filter_query_by_relationship', 10, 1 );
/**
 * Filter the main query by using URL parameters
 * 
 * @param object $query WP_Query.
 * @return object
 * 
 * @since 3.6.8
 */
function rel_filter_query_by_relationship( $query ) {
    
    $id     = $query->get('relation_id');
    $from   = $query->get('relation_from');
    $to     = $query->get('relation_to');
    
    if ( ! empty( $id ) && ! is_admin() && $query->is_main_query() ) {

        if ( ! empty( $from ) ) {
            
            $query->set( 'relationship', 
                array( 
                    'id'  => esc_attr( $id ),
                    'from'    => intval( $from ),
                )
            );

        } elseif ( ! empty( $to ) ) {

            $query->set( 'relationship', 
                array( 
                    'id'  => esc_attr( $id ),
                    'to'  => intval( $to )
                )
            );
        }
        
        
    }

}

add_filter( 'query_vars', 'rel_add_query_vars' );
/**
 * Add query vars to build query with URL parameters
 *
 * @param array $vars WP_Query variables.
 * @return array
 * @since 3.6.8
 */
function rel_add_query_vars( array $vars ) {
    $vars[] = 'relation_id';
    $vars[] = 'relation_from';
    $vars[] = 'relation_to';
    return $vars;
}

add_action( 'mb_relationships_init', function() {
    MB_Relationships_API::register( array(
        'id'   => 'practices_to_persons',
        'from' => array(
            'object_type' => 'post',
            'post_type' => 'practice',
            'admin_column' => 'after title'
        ),
        'to'   => array(
            'object_type' => 'post',
            'post_type' => 'person',
            'admin_column' => 'after title',
        ),
    ) );
} );