Hi Edwin
What does the compass say. Is it pointing to something? Can you post a screenshot please. You said you completed the mission. Did you press "Esc" to exit the mission?
Try this. When you start FSX, go to the Free Flight screen and LOAD a previous saved flight from an earlier time. Check the box to make that flight the DEFAULT. That's the check box at the bottom of the saved flights list window. Start the flight and fly around. Is the mission pointer gone?
If it is, then save the flight, and make it default again, then press "Esc" to exit the flight.
I use to have FSUIPC "auto-save" my flights at regular intervals to a flt file named "Previous Flight, in case my PC crashes? Then I could restart at the last auto-saved position. So when I fly a mission, it was saving to my "Previous Flight" save file instead of the mission save file. It saved to my free flight save file as a mission causing similar results you described when I load the "Previous Flight" file in free flight. If you do that, you should turn auto-save off while you fly missions.