Hi Adriano,
I have made the change, but remember you have admin access to the site, so feel free to make changes to wp-config, and update or switch off plugins as you see fit to debug the issue.
I cannot put a public link to the site on here, but if you click on 'Buy Tickets' in the nav menu, it will take you to a list of 'Shows' (CPT). Every Show page is affected. They all use the Content templates 'Show Template' (main area), and 'Show Widget' (sidebar). Click on any one to see the problem.
My other CPTs are affected but if these pages work then the issue will be fixed across the whole site.
Thanks.