I have quickly checked your site the Contatti page has some mandatory custom fields hidden link which needs to filled up in order for the page to be published or save, To confirm the issue I have filled up the fields with sample contents after which i am able to save the page with out any issue and the page can now be accessed here hidden link
I have also tested the issue on a sample page which i am not able to reproduce the issue.
In case, If the issue is something different, Please let me know the steps on how to recreate the issue.
Please Goto Toolset > Custom fields , Edit the "Dati genitore" Field group . On the field settings You have added the condition to Display when Any of the conditionals are met change that to All conditions are met that should resolve the issue for the time being.
I am also checking this case why the field groups are displayed on pages even if they are set to display only in Post type Modelli