Last night I experienced a new and troubling behaviour of my MA.  In summary my MA and controller disconnected at very short range and refused to reconnect until I restarted the controller after the MA RTH landed itself.

MA ~ 2 months old, 78 flights / 16.5 hours / 188km logged without a single bump or touching the props on anything (other than unfortunate flies).
Controller and MA running latest F/W.
Manual Wi-Fi set as I always do to avoid 5.8GHz cr@ppy UK range, possibly I had it on channel 12 (2.4GHz).
Full MA battery, ~75% controller battery.
Launched after good GPS lock, using precision landing (glad I did!), well away from buildings and other Wi-Fi interference.
Switched to sport mode, full speed up.
Replaying flight log: flew up to 120m, just 110m horizontally away from me on the ground.
Message about maximum altitude reached 120m.
Message about high wind velocity, fly with caution.
Message about signal lost, MA immediately started returning to home, I thought odd at that range, there were no messages about strong interference.  Expecting to regain control as the MA got closer which is what happens every other time I lost signal.
No control was regained, app said connection lost the whole time, no video updates.
MA flow horizontally to take-off position, then started descending.  Luckily it did a very accurate precision RTH landing within ~2 feet of where it took off.  I took off on a concrete area about 4 meters away from the sea.
Watched the MA land 2 meters in front of me with no control what so ever, app still says disconnected!
After landed and props off, restarted the controller.
Connection immediately resumed however it had switched to auto Wi-Fi channel selection and 5.8GHz.  Never before has it switched itself out of manual to auto, so something happened in the MA and controller comms to cause this complete reset or whatever.
Took-off and continued flying until battery low, no more problems experienced.

As a precaution, 99% of the time I use precision take off because it might save my drone one day if I drop the controller or it fails for some other reason.  Some instinct tells me to do this and last night it absolutely paid off.  Very thankful that precision RTH works well and my MA did not end up in the sea or wrapped around some metal railings.

I have the same problem and DJI still not provide the reason.

https://forum.dji.com/thread-144319-1-1.html

This issue is a huge problem if drone force landing and you lose control. May i know what frequency you have when it lost connection? 2.4 or 5.8? Mine still able to go up to 2.7km one way in urban area with 5.8Ghz, all auto and i did not fake gps to USA.

I am in 2.4 and the problem is not related to distance. I fly over 300 meters without any problem and the Air suddenly disconnected 20 meters away. I can’t reconnect after it RTH and need to restart RC. Fly again in same path to check and no problem at all. Looks like the communication part crashed in RC or aircraft and need reset.

This problem occurs only 2 times for me. I have no idea how it caused. I am using iPhone with latest firmware and Go. It’s not a big concrete for me but I won’t fly Air in risky place because this issue. Need to consider aircraft may disconnected anytime and unable to connect again.

MA disconnect from controller at very short range happened again last night, at the end of a flight.  Literally in a field 49m from the controller and 24m high according to playback.  Latest firmware in both MA and controller.  Controller needed a power cycle then it reconnected before the MA had RTH landed.

DJI?

AndrewUK Posted at 2018-8-7 09:51
MA disconnect from controller at very short range happened again last night, at the end of a flight.  Literally in a field 49m from the controller and 24m high according to playback.  Latest firmware in both MA and controller.  Controller needed a power cycle then it reconnected before the MA had RTH landed.

DJI?

I had disconnect issues as well so downgraded DJI go4 app to 3 prior versions and seems to be working well now.

forager3215 Posted at 2018-8-7 09:56
I had disconnect issues as well so downgraded DJI go4 app to 3 prior versions and seems to be working well now.

What version is that?

If this happens again, you can also try restarting the rc. I seldom have this happen but that usually fixes it.

AndrewUK Posted at 2018-8-7 10:20
What version is that?

Version: 4.2.12 (2031018) for Android 4.4+ (Kitkat, API 19)

Can get prior versions here
https://apkpure.com/dji-go-4-for-drones-since-p4/dji.go.v4