There are likely 2 causes here.
One is, because the vertical result item height was set to 10%. It means that it will adopt to the parent document height. I have changed that back to 'auto', as per the default value: https://i.imgur.com/dn2mhDm.png
However I was not able to test it, as I can't clear the site cache on the front-end. It still shows the previously cached asset content.
Another, more serious issue is, that the results container is wrapped within a
HTML element. That can completely mess up the styling, so I the shortcode should not be wrapped by that: https://i.imgur.com/B6V8PzG.png
If you use a visual editor of some sort, try a different block there, maybe a HTML instead of a Text block. Text blocks tend to use the 'pre' tag for preformatting.
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