This is a battery calibration issue. We have had the battery go from 30% to 0% instantly and the aircraft just tries to make it to the ground as soon as possible.
DJI recommends taking your batteries down to less than 10% (we go to 8%) and then doing a FULL recharge on the STOCK CHARGER. "Full" is emphasized because partial charges will mess up the calibration faster and "stock charger" is emphasized because charging hubs and 3rd party chargers will not do the calibration properly.
The settings in the DJI Go app really only affect when the warning beeps will occur. If the aircraft senses that it only has enough battery to get home it will start heading home regardless of setting.
Map Pilot will never just go into hover mode unless the Stop button is pushed. Map Pilot is either on the way to a mapping grid, on a mapping grid or on the way home.