History Query missing wind data

I'm trying to run a history query that involves getting the windspeed. However, regardless of location or time window, the queries all return None for the mean_wspd value. Is there a query parameter I'm missing?

Thanks!

Query

https://weather.visualcrossing.com/VisualCrossingWebServices/rest/services/weatherdata/history?&aggregateHours=01&unitGroup=us&contentType=json&extendedStats=true&includeAstronomy=true&dayStartTime=06:0:00&dayEndTime=22:0:00&startDateTime=2020-01-15T00:00:00&endDateTime=2020-01-16T00:00:00&location=39.2143%2C122.0094&key=YOUR_API_KEY

Sample partial query result

{'wdir': 280.0, 'sunrise': '2020-01-16T07:09:56+08:00', 'datetimeStr': '2020-01-16T22:00:00+08:00', 'mean_humidity': 53.77, 'min_heatindex': None, 'min_humidity': None, 'cloudcover': 0.0, 'mint': 24.8, 'datetime': 1579212000000, 'precip': 0.0, 'solarradiation': None, 'mean_wspd': None, 'dew': 10.4, 'precipcover': None, 'max_heatindex': None, 'max_wspd': None, 'info': None, 'temp': 24.8, 'min_windchill': None, 'maxt': 24.8, 'visibility': 6.2, 'max_humidity': None, 'mean_heatindex': None, 'min_wspd': None, 'solarenergy': None, 'max_windchill': None, 'weathertype': '', 'moonphase': 0.72, 'mean_windchill': None, 'snowdepth': 0.0, 'sealevelpressure': None, 'snow': 0.0, 'sunset': '2020-01-16T16:53:14+08:00', 'wgust': None, 'conditions': 'Clear'}], 'id': '39.2143,122.0094', 'address': '39.2143,122.0094', 'name': '39.2143,122.0094', 'index': 0, 'latitude': 39.2143, 'longitude': 122.0094, 'distance': 0.0, 'time': 0.0, 'tz': 'Asia/Shanghai', 'currentConditions': None, 'alerts': None}