post excerpts going into thumbnails for su_post

Hi

I used the su_post shortcode to display 8 posts with the default loop on my 404 page. Do you know why the post excerpts are going into the thumbnail images for each post displayed? Use this broken link to get you to my 404 page: https://www.mailshark.com.au/recent-security-news/url. The posts are under the search bar. Can you provide a fix for this formatting issue or help me try and fix it?

https://www.ads-software.com/plugins/shortcodes-ultimate/