Hi
The main content block may be hidden on the homepage profile.
Go to extensions> Template manager > Ja bistro and check if a profile is assigned to All pages and some other profile is assigned for the Home page. If you dont want to use different profiles, you can simply remove the page assignments and make sure the profile you are using for all pages is set to show the Main Content Block from its params.
If you want to use different profiles for Home and remaining pages, then set to show the Main content block from the profile assigned to homepage.
Hope this solves the issue. If you still need help then please provide your site url and admin details at http://support.joomlart.com/index.php?/Tickets/Ticket/View/78197