When playing back your content the browser-app is empty. When editing a page with a browser-app on it the app is empty or a popup is shown warning about the fact that cookies could not be loaded.
The Google Chrome, Chromium, Firefox and Edge browsers have changed their approach to handle "third party cookies". This change is meant to improve the privacy of the browser user by making it difficult for companies to track the users behaviour online. A positive change. However, since these snooping companies misuse a relatively innocent concept of the web browser the measure that was taken did not only make life difficult for malicious companies but also everybody who used this innocent concept for the benefit of the browser user.
The best solution should also make sure the web page app will work for the future;
Until version 94 of Google Chrome it is possible to fix this problem without enforcing HTTPS playback by using the
command line option when starting up Chrome. This command line options can also be used on Chromium and Edge. For Firefox there is no such option. Since this option is a temporary workaround at best we strongly suggest you use the solution described above.