Inconsistent response from FlightInfoStatus

https://flightxml.flightaware.com/json/FlightXML3/FlightInfoStatus
When I call this endpoint with the proper airline icao and flight number I get an inconsistent response where sometimes it will show an actual_departure_time key and sometimes the key doesn’t even show up.

Is there a reason for this? Couldn’t you guys add a default value so that the API is consistent?

Also there are a bunch of fields that don’t always appear in the response (i.e codeshares)

Is this a bug? I feel like you should be consistent and return the same params every time (just set a null value to the ones with no information)

If the flight has not departed yet, then actual_departure_time will not be present. Similarly, if there are no known codeshares for that flight, then it will be absent.

Those fields are noted in the FlightXML3 documentation with ? character suffix as being optional: FlightXML3 Web Services