Latest post won't display featured image on WordPress site (featured image turned on).

I think my problem is an easy one to solve, yet I'm getting no help from searching online.

I'm running the eleven40 pro theme on the Genesis framework. If you click the link, you'll note that the sample page clearly shows a featured image on the most recent post.

Unfortunately, in the case of my site, every time I make a new post, which sits at the top of the page/post feed, it won't show a featured image. This, despite having them turned on and an image selected.

Strangely, once I make a new post, the previous one is pushed to the bottom section of the site and the featured image then (finally) displays.

*Please note that I've purchased the theme and framework from StudioPress (no dodgy freeware here). Unfortunately, their help forums are a graveyard these days.