If it's only happening at or close to the level of the launch point, it probably isn't the VPS data, but it's quick and easy to check and confirm.
Post the flight data from a flight where it's happened.
Go to
DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report of the flight.
Come back and post a link to the report it gives you.
Or .. just post the txt file here.
I don't have a lot of confidence in the advice that some DJI support people give.
What re-calibration did they recommend?
