If you see suggested items returning no results, you can check if there are any applied filters in your Query Suggestion setup and make sure you have records that match those filters.
You can write a script that checks and creates a new filtered query suggestions index based on your first one, ensuring that it will have matches.
To do this, you can browse your query suggestions index, and for each suggestion you find, run a search using the suggestion and the filters you are using on your site. If the search finds a result then you can add this suggestion to a new "filtered query suggestions" index, and if not you can skip it.
Of course this would require a significant amount of coding and would also use search operations.
Second option is to remove specific keywords and hide the keywords you don't want to show.
There are more details on how you can modify autocomplete here: https://www.algolia.com/doc/api-reference/widgets/autocomplete/js/