Problem themify ultra on wordpress – Responsive Issue

I am running a WordPress site using the Themify Ultra which is the basic theme and I used themify builder to create my custom theme. When I enable the responsive feature, I have no results on the phone. When I try to acces the site from mobile from I have a white box on the right part of the website. I don’t have the same problem on all pages, just first page.

To my understanding, is this a common issue with responsive themes ?