Thanks. I see this is for a Zoom model, my model is not zoom but the manual says the same thing regarding Failsafe RTH. However, this is all confusing. If the drone looses connection with the controller (NOT totally but say it just gets a low signal and you lose video) then a SMART RTH can be used. In my case there was a total disconnect. Only a non moving B and W video screen image and all buttons greyed out. No control-- no way to initiate RTH. According to the manual, it should have (via Falisafe RTH) started home almost immediately, but did not. After about 5 minutes, I left to go to the location where the drone was when it disconnected from the controller. I was looking for it when my wife called to say the drone had returned and landed safely. The battery was almost depleted. I flew it several times after this with no problems, but DJI insisted I send it to them to be checked. They found nothing wrong and it is on its way back to me.
Here is an interesting point but not an answer: "If the remote control signal is re-established within 60 seconds of Failsafe RTH being activated, the aircraft hovers at its present location for 10 seconds and waits for pilot commands." In this case NO signal was reestablished so as per programming the drone then RETRACED its course for 60 seconds (away from home base), and then flew in a straight line home. "If the remote control signal is still lost 60 seconds after activating Failsafe RTH,( it was) the aircraft stops retracing its original flight route and flies to Home Point in a straight line." So maybe the drone flew AWAY from home for 60 seconds and then flew STRAIGHT LINE back home. But there was about 65% power left when the disconnect occurred so an extra 2 minutes or so of flight should not have depleted the batteries and it should have returned to home within 5 minutes, at most. So, this analysis is not really an answer.
Thanks for your interest.