[OnePress] iFrame not displayed

Hi there,

I would like to insert maps as iframe either from Google or uMaps on the contact section.
Inserting the code in contact text box is ok (the code ans the map are showed).
After publishing, the map itself is not displayed on the site (just the link for full size).
Next, when i get back on personalization, the iframe code is no longer present.

How should I get rid of that?

Thank for help