CMS Pages get "You are not authorized to view this page" at the bottom of a page that otherwise renders correctly

1. Navigate to Content Management > Sites.
2. Select a site (for example, Employee Self-Service).
3. On the Pages related list, click New to create a new content page.
4. Populate Name of the new page (for example, test_page) and save the record.
5. Scroll down to Related Links and select Edit Page.
6. Click the Add content link in the upper left and select any gauge (for example: Gauges > Incident > All incidents By State).
7. Test the new page by launching with this URL: https://<instance>.service-now.com/ess/test_page.do.
8. At the bottom of the page with the correctly rendered gauge, the message You are not authorized to view this page appears.

Reload the page or the URL and the incorrect security message is cleared.