Using Heading Block layout

I have implemented the heading block layout as suggested here: https://displayposts.com/2019/02/26/use-headings-for-post-listing/

But using shortcode [display-posts id=”7451″ include_content=”true” layout=”heading-block”] will show ALL posts not only the ID i have set, as well as limit=”1″ will have no effect. Is this feature broken?

Any support to this is appreciated, thanks.