Why does this happen?
Sometimes the tracking script wasn't properly loaded and detected on the page. This can happen when there is a consent modal on the page that requires a visitor's action before loading the script. Or if the page you are checking is behind a login page. Or if using Google Tag Manager (for example) is not firing on the page. Other times, the script really is missing
Solving the Error
You can perform a manual script check to see if it's installed correctly.
If you are still having trouble, please send us an email. Please include the name of the Snapshot and page URL.