In the web of flightaware the flights of (QL2967, B62830) do not appear for the day 20/04/2019
These flights exist for that day, why do not these appear on the web?
A cancelled flight (actualdeparturetime == estimatedarrivaltime == actualarrivaltime == -1 in FlightInfoEx) will still appear in FlightXML, but may be hidden from the activity log on the website.
In this case it looks like QL2967 is no longer operated, but some automated schedules are still received. B62830 appears to be a flight number no longer used by JetBlue.