Zerif Lite testimonial section doesn't appear correctly

Hi,
I use Zerif Lite template for monthes now and I like it very much. Everything worked correctly. After a hacker attack, we had to refresh the template as well. Now it is clean and everything works except the testimonials section.
The headline and the block is visible, be the opinions couldn’t show up. I checked everything, I followed the steps of the user manual of Zerif Lite but nothing change. I read in this support forum about the same problem and the guy solved the problem that there was a plugin which wasn’t compatible with the template but he didn’t write which was the plugin.
The tricky thing that the testimonial worked for a long period and I haven’t install any new plugin so far.
Do you have any idea how to solve it?
Thanks!