How to integrate a facetted search

How can I enable facetted search with this plugin. I have read the documentation at
https://github.com/parisholley/wordpress-fantastic-elasticsearch/wiki/Faceted-Search

and I understand the concepts behind passing a query with es containing the facets to filter on. However when I pass a url with es parameter set through elasticsearch\Faceting::urlAdd or formed manually the results returned are not filtered on the facets e.g.
?s=cats&es[category][and][]=vets

and the query

?s=cats&es[category][and][]=management

return the same results so the facet search is having no effect

however I can see that the facets are being correctly indexed when I run the following code on the same page

$search = 'cat';
$facets = elasticsearch\Faceting::all();
$facets = array('category');
$return = elasticsearch\Searcher::search($search,  0,  10, $facets ,  false);

because the return array contains counts for the matches within each
facet.

This is a gap in the documentation and not a bug – but make use for facets impossible.

https://www.ads-software.com/plugins/fantastic-elasticsearch/