Nginx Collapsing Empty Variables in Access Log

access log configuration

  log_format                    main
                                '$server_name'
                                '	$msec'
                                '	$remote_addr'
                                '	$http_user_agent'
                                '	$cookie_uid'
                                '	$cookie_sid'
                                '	$cookie_lis'
                                '	$cookie_ffs'
                                '	$device_map'
                                '	$request_method'
                                '	$host'
                                '	$uri'
                                '	$args'
                                '	$http_referer'
                                '	$request_length'
                                '	$gzip_ratio'
                                '	$status'
                                '	$request_time'
                                '	$bytes_sent'
                                '	$upstream_addr'
                                '	$upstream_cache_status'
                                '	$upstream_response_time';
  access_log                    /var/log/nginx/access.log
                                main;