place a piece of sheet metal over the gps ant. to block the signal to the EVO. i think DJI MAvic owners do this trick to get around the GEO fencing..
let us know how it works
There is an ATTI mode that is activated when there is weak gps signals and when the vision sensors do not have enough light to operate. One night I wasn't receiving more than 5 or 6 satellites and it went into ATTI mode. It definitely will drift in that mode. Be careful