Don't have the time to debug right now, since I don't know how to debug Elasticsearch and/or this plugin, but pagination is not working with plugin enabled. Pagination works when plugin is disabled.
You need to implement your changes to query_posts as a filter, not rewriting it in your search.php (elasticsearch and main query is done prior to this template being loaded).
Don't have the time to debug right now, since I don't know how to debug Elasticsearch and/or this plugin, but pagination is not working with plugin enabled. Pagination works when plugin is disabled.
http://example.com/?s=test&paged=2 ends up in 404, even though there's 42 pages of results.
My search.php is basically like this: