Why is the preview of search results not showing on a Wordpress site?

Question

WordPress

Welcome all! There was such a problem with the search on the site - https://www.buildbody.org.ua/ . Previously, at the initial text input, possibly suitable results appear under the search bar, that is, before a person clicks on the search, articles are displayed just below that contain the word that the user enters.

Now, even when you fully, correctly enter the word, for example "protein", it is displayed in the preview below that no results were found. Although when you click on the search for this word, everything is found without problems.

What is the reason, how to fix it!? Help me to understand!