[Google translate] :-)
Hi everybody.
I have a rather annoying bug for a few weeks with iOS and my P3Pro.
Everything worked fine until the HomePoint no longer wanted to be registered (with DJI Go or Litchi) but only under iOS.
Everything goes very well under Android.
I thought at first that it was my usb cable that shit, but the bug persists with any official Apple cable or not.
I have uninstalled / reinstalled DJI Go but still nothing.
The lights are green on the drone, indicating that the lGPS signal is acquired.
Calibration is done just before.
The 2 messages are: "Point Home not registered" and "The GPS signal of  the mobile device is weak and the location can not be carried out".
The app clearly indicates 18 satellites acquired and "Ready to Go (GPS)" is green.
I tested on my iPhone 6S Plus (iOS 10.1.1), on the iPad mini Retina  (iOS 9.3.5) and the iPhone 5S (iOS 10.1.1), none allows the acquisition  of HomePoint.
The only divergent point is the OS (iOS / Android).
DJI GO iOS: v3.1.0
Device: v 1.9.60
Remote control: v1.8.0

thanks.

Check if location services are enabled in the iPhone for the GoAoo and if there is any issue with other apps using location information. Does not sound like a DJI problem

Everything is well configured. I did not touch anything. I just updated the DJI GO application on both iPad and iPhones.

OK. I found the problem. I AM the problem. I did not start engines when activating the home point, while I was doing it with the Android smartphone.