Hello!
First of all you did a very good job, i like this theme very much. But unfortunately i have an issue with the Visual Composer. I am using WordPress 4.9.1 and I have the Version 5.2.1 of the Visual Composer installed. I recognized that the Visual Composer does not work correctly. To fix this problem i tried to update the Visual Composer to the latest version. But in my case this does not work. When I navigate to WP admin -> Appearance -> Install Plugins i have no option to update the Visual Composer.
I tried to deinstall the Visual Composer and install it again under WP admin -> Appearance -> Install Plugins. In the column Version i get an Error for the Visual Composer: