No thumbnails showing in categorys

When you click on Category and it goes to that page, the thumbnail doesn’t show. I would like the images to show on top of the article excerpt.

I have tried CSS codes that were recommended for similar issues but I can’t get images to show up at all.

Hello there,

It should be displaying by default. See our demo’s archive link:

Probably do you have different page? Please share its link here, so I can have a look.