404. That’s an error.
The requested URL /start_preview/opt?uiv2&id=GTM-KHHN7J5>m_auth=ZS0cnXVxWa92tfbWpjxtxg>m_debug>m_experiment=GTM-KHHN7J5_OPT-5WG2M%24>m_preview=QUICK_PREVIEW&redirect=https%3A%2F%2Foptimize.google.com%2Foptimize%2Fsharepreview%3Fid%3DGTM-KHHN7J5%26gtm_experiment%3DGTM-KHHN7J5_OPT-5WG2M%2524%26url%3Dhttps%253A%252F%252Ftnmtraining.wordpress.com%252F%26opt_experiment_name%3Dhttps%253A%252F%252Ftnmtraining.wordpress.com%252F%2520%282%29%26container_name%3DMy%2520Container&optimize_editor
was not found on this server. That’s all we know.