The hits and aggregations property are not set correctly in the _handleResponse function
_handleResponse: function(request) { var response = request.response; this.aggregations = response.aggregations; this.hits = response.hits; this.fire('results', response); return response; }
Direct assignment does not work because the properties are declared as read only (see https://www.polymer-project.org/1.0/docs/devguide/properties.html#read-only)