Thanks all. I think I have my iPhone compass "on" and calibrated now. I tried using the "Compass" app on the phone and it was unresponsive. I went into Settings - Privacy - Location Services and changed the Compass App to "While using". Still it was not responsive. Then at the bottom of Location Services is "System Services". I went there and switched on "Compass Calibration" and now at least my phone's compass seems to be working. I also recalibrated the compass on the drone. I'll find out today when I fly (winds permitting) if all that helped at all.