I just completed a cross race. Eveyone who had a Garmin has the correct(ish) altitude. From my Magellan Strava recorded a zero altitude. Go to Magellan and I find I should have had 70 meters. Erase...
Yes, I have a cross race where all those who uploaded from a Garmin had the corrected altitude, mine show Zero, yes nothing! So an ability to edit the altitude would be handy.