Streamline – Problem Getting Featured Post Pics to Work

I know it’s possible because if you look at the features posts in the streamline demo (https://www.studiopress.com/demo/streamline.html) it has nicely places 150px x 150px pictures within each featured post.

For some reason I’m unable to replicate that in the blog I’m working on. Can’t even find the option within the edit post page to do so, nor any other settings page.

Has anyone been able to make it work with the StudioPress Streamline theme?

edit to add: The blog URL is https://www.vastudesign.com.au/wordpress

Cheers.