Just to follow up. I've been able to check your site. You are running Preachit 4.1.9 with Joomla 3.7.3. Because of changes in this Joomla version the old code for tabs needs to be modified. This was done after the issue was reported and an updated version released about 8 hours after 4.1.9 was released. You'll need to update to 4.1.10 which is the latest version on our site in the download area.