When/why does ‘$query->get( ‘tax_query’ );’ return empty?
AFAIK $query->get for main query works only with public query vars, i.e. vars that can be triggered via url, but nothing prevents to directly access directly to tax_query property of query, but notice that it is an object, instance of WP_Tax_Query and the current queried taxonomy arguments are in the queries property of that object. … Read more