Hi,
Thank you very much for the details!
I checked your configuration and everything seemed to be setup correctly. The page did not show up in the search results page, because the search override was not triggered. It happens sometimes with custom made results pages or in cases where a custom code is used instead of the actual search query, or the query is altered in a different way.
Anyways, I have enabled this option to make the override more aggressive, now the results page should contain more results.
I strongly recommend using the default query to fetch the posts on the results page following the WordPress theme coding guidelines, otherwise some unwanted results may appear. Custom made results pages are usually built for specific queries and ignore the original, and an “override” may add items to those queries, which are unwanted.