After doing my pre-checks through DJI GO App, and commencing my DD mission it finishes the mission then just starts flying away in a completely different direction from where it took off.  RTH button on both DD and controller, no response.  Very baffled.  I followed it and was able to land it manually, but am very confused on why it would go to a completely different "Home" location.

New to this, so any help would be nice.

All Firmware up to date
P4A
Samsung Tab 8
Android V 6.0.1
Compass Calibrated before flight
RTH set in DJI Go before DD Mision.
In DD Home was shown where it was taking off from.

The only way to know would be to look into the flight data.
This might help you:  https://support.dronedeploy.com/docs/gathering-flight-logs

If you want help with it, try to use the Healthydrones (now called Airdata) option.
But make sure you tick the box to share information becayse the CSV firl is essential for investigating.
Then come back and post a link to the Airdata report.

Did you try cancelling the flight by flicking the flight mode switch out of P-GPS mode and back again?
That usually cancels the mission and allows you to resume control.