Updated to the new firmware on 04/14/17 went outside and did a recalibration on the compass, reset my RTH altitude to my normal 40m, and distance to 1609m. Reset my home location, and then took off. It flew well, so I wanted to check out my RTH. I took it out to 110 ft high, and 120 ft out in distance. Hit RTH on the controler as I always do, the Mavic turned to home, and rose to 40m, moved foward about 2 ft, stopped, and rose another 30ft and just hovered. I cancelled RTH and tried to bring it back, I was able to lower it ok, but everytime I went foward on the stick, it would give me a braking warning, please center stick. I limped it home and went on line with DJI. I was told to not only recalibrate the compass, but also the gimbal, and IMU's. Did that, took off, and once again, and it did the same thing. I then called DJI, and spoke to a tech, and after telling him a couple of times just what was happening, he had me change the RTH from 40m to 20m and try to fly and RTH again. I changed the RTH to 20m and did another compass recalibration, and new home location. I took off, and brought it out about 120ft out, he wanted me to RTH, but I told him at 20m I would hit a tree line, so I can not go that low( which is why I set it to 40m). I told him I will fly it back home and reset RTH altitude to 40m again, take it out with him on the phone and tell him just what was doing as it was flying. I took it up about 110ft high, 120ft in distance, hit RTH, and the friggin thing did what is was told to do. I tried it a second time, and had the same results, with the only issue being that it was about 8ft away from home point both times. Still do not know why it would not work the first time after the update. I did another compass recalibration after I hung up with him, and it hit the RTH home point right on the money. Going to fly, but not to far away a few more times today and check RTH before I go longer and higher, not trusting it yet.

So far new firmware is doing just fine.  Out of at least 9 flights, the app disconnected as I was about to land.  Flew out ro 1685ft and also did active track and POI orbit of my house.  Tried RTH 3 times and all did as advertised.  I think the disconnects occurred when I was near our aluminium flagpole.  Last 3 flights, no issues.
Did you check your home point?  Did you try the RTH button on the RC?

Was the sun low in the sky? It sounds like to OA sensors were interpreting that as an obstacle.  (This is not related to the update)

Bill in Ohio,  the home point was set before takeoff, and checked on the map, no issues, and I always RTH on the RC. and WolfgangStiller, the sun was still high here. I did fly again yesterday, 04/15 and had no issues again. Took it about 1/8 mile out, and around 120ft high, did a RTH and  landed on the mark.

Bruce N Posted at 2017-4-16 05:26
Bill in Ohio,  the home point was set before takeoff, and checked on the map, no issues, and I always RTH on the RC. and WolfgangStiller, the sun was still high here. I did fly again yesterday, 04/15 and had no issues again. Took it about 1/8 mile out, and around 120ft high, did a RTH and  landed on the mark.

The sun does not need to be directly facing the Mavic for OA to kick in.  It can also be the angle of the sun to the Mavic sensors. Just be aware of it and fly accordingly. It is mentioned in the manual so I am surprised that support did not suggest it.