Desired page not showing

Try to retype the quotes in the shortcode. This can be the root of your issue.

Thanks for your very quick reply. I had typed the quotes myself. I tried again by retyping the quotes but I can’t see anything. Can you successfully see my iframe content in your wordpress?

Yes, its working for me.

Can you share the URL of the page with the issue?

Sure, here you are

https://mio.com.unica.it/wordpress/mariorossi/

Thanks for your help.

The error from the Chrome’s console on that page:

Mixed Content: The page at ‘https://mio.com.unica.it/wordpress/mariorossi/’ was loaded over HTTPS, but requested an insecure resource ‘https://newton.nes.aau.at/~sulfurous/app.html?id=11397100&turbo=false&full-screen=false&resolution-x=480’. This request has been blocked; the content must be served over HTTPS.

Both pages (parent and embedded) should be loaded via same protocol (http or https) because of security reasons.

Thanks a lot for your help.