wp-includes/cron.php の248行目の以下の数字を変更する
変更前
wp_remote_post( $cron_url, array( ‘timeout’ => 0.01, ‘blocking’ => false, ‘sslverify’ => apply_filters( ‘https_local_ssl_verify’, true ) ) );
変更後
wp_remote_post( $cron_url, array( ‘timeout’ => 5, ‘blocking’ => false, ‘sslverify’ => apply_filters( ‘https_local_ssl_verify’, true ) ) );