I'm surprised they let you set the rth that high. He must have thought he was setting it to 396 feet. Government regulations forced DJI to make it so light, so they are partly responsible for these mini wind loses.
RTH should be set based on the environment of the immediate flight. 300ft RTH is too high unless your are in an environment with very tall obstacles. In this case the OP literally didn’t take the time to prepare for his flight.
