Thanks for that. I can see from the results that doc_count_error_upper_bound >0 which means that the not all of the relevant data is being returned for consideration to the coordinating node.
This means that the number of partitions is too low for the size of results being considered. By increasing the number of partitions you will be reducing the number of terms being considered in any one request to a manageable subset and you should see the doc_count_error_upper_bound value become zero (meaning nothing was left behind on shards).