After installing GreatMag theme, no pictures shown

I have a magazine portal with news and pictures.
If I use themes not from your company, all the pictures are shown.
I installed, actived GreatMag, and the pictures are not visible.
Take a look http://www.nosotros.com/

Hello,

Did you set featured images?

Kind Regards, Roman.

It works for a new post, but
this site was created several years ago.
How I setup all other posts with images to show up?

It is GreatMag pro…

Hello,

Did you set featured images for each of your old posts as well?

Kind Regards, Roman.

I published more than 2,000 posts…
It is almost impossible to do that to each one!

Hello,

You can try to do it automatically. But please make a full site backup first (files and database).

Please check these links:


https://www.gavick.com/blog/wordpress-automatically-set-post-featured-image

Kind Regards, Roman.