Hi,

Yesterday I took my drone out for another flight session. I've practised  launching and landing Mavic in my hand and it worked very well. I've  disabled the landing sensor and the landing operation went pretty  smooth.

Apart from that I also bought a new battery and the strange behaviour  started here (I guess). When I switched batteries and start flying  again, I've noticed that randomly the video feed was lost and the  controller behaved like the drone was landed because when I tried to  change flight mode I received a warning saying that the drone needed  to be flying to change modes. Every time I landed the drone the video  feed came up again. While the video feed was lost I could start/stop  video recording and pilot the drone without any problem but I didn't  try to reset the app, I was afraid of what could happen.

Does batteries have firmware and need to be updated? That could be it  because I bought the battery and I've used in the field without testing  it at home (I've only recharged it to 100%). I've tested powering up Mavic with both my  batteries and DJI Go 4 says firmware is up to date (for both).

Any ideas of what could have caused this behaviour? Have any of you experienced this?
Thanks for your time.

ps: I posted here too.

Does batteries have firmware

Yes.

[Does the battery firmware] need to be updated? That could be it

I doubt it; it doesn't seem very likely that the battery firmware would cause the behavior you described. But just to be sure you could always alternate batteries a few times and see if there's any consistency to the behavior that really is associated with the new battery.

Any ideas of what could have caused this behaviour? Have any of you experienced this?

No idea, and I hadn't heard of this one before. The only thing I could suggest is to upgrade or refresh the firmware in the controller and Mavic itself and see if the problem persists. If it does, then you should open a case with DJI and let them know what's going on, and they may want to send you a replacement.

Could you please clarify what mobile device you are using?
Please try to go to another place to test again.

This happened with the new battery, with the original everything was fine. I'll try it again this weekend.
I'm using an iPhone 6. How can I refresh or force a firmware update/refresh? I've tried to search for that option in the app but I could only see the app start firmware confirmation message (and it was all updated).

Thanks.

So today I took my bird for another flight session. Everything went well, I'm getting more confident and happy with Mavic.
Regarding the video feed issue I think I have a clue. Lately I used to fly Mavic in zones with intermittent cell phone signal (3G/4G) and I guess that drop of signal is what's causing this trouble. In the first flight of today Mavic stopped transmitting video feed seconds after taking off and I've noticed that my iPhone 6 lost cell phone signal. So I moved myself 5/10m from original point (same flight zone for Mavic though) and I did not experience any loss of video feed.
And now that I think of it, last time I had this issue I was in an area where we've poor cell phone signal.

Could this be it, or it's just a coincidence? Can I fly Mavic in airplane mode (with wireless on)?

Thanks.

Today I went back to the same zone where I've experienced video signal loss and I was able to reproduce it.
When I start flying Mavic with 3/4G if I lose phone signal I lose video signal too and a few seconds latter a popup shows asking if I want RTH due to video signal loss. I've pressed "No", moved to a better phone signal zone, and video feed came up again.

This problem still persists. Now that I'm on vacations I'll try to test  it better and simulate an alternation between Wifi/4G/no signal, I put  my money on that network switch...