Updated to v01.04.0400 this morning and test flew with 3 batteries.  All appears fine.  In fact I think flight performance has improved; it's a shame I haven't got a 2nd Mavic on previous firmware to compare to. I'm still on DJI Go 4 v20 Key observation below:

  

  

1.  Update worked fine through assistant 2. No battery updates required. I did RC connected to PC via usb and AC connected wirelessly; update both together.

  

2.  All my flight settings remained in tact.  Which is good, cause I always forget to write them down after spending hours tweaking.

  

3.  App remained stable through all 3 batteries.

  

4.  Video and photos performed as expected. No problem.  Lag to my Nexus 7 is possibly slightly improved.  I experienced no video stuttering or pixilation; I had this occasionally on previous firmware.  Probably just coincidence though.

  

5.   Flight performance definitely appears improved. I can't remember ever getting 46kph out of the Mavic (not in sport mode) before.  It was a dead calm morning. Speed isn't really important to me, but was a good indication that performance has improved.  

  

6.  The Mavic definitely transitions from movement to hover in a smoother manner (same brake settings).

  

  

I hadn't really noticed before that the Mavic flies much slower with obstacle avoidance enabled.   26kph with obstacle avoidance enabled – 46kph with obstacle avoidance disabled; every day is a school day.

So, as far as I can see thus far, latest Mavic firmware update is good and a positive experience.  Phew!

you have me convince,  will go ahead and install, thank you for the info .

Hi, thank you for sharing your experienced. Enjoy and have a safe flight.

Thanks for posting your observations.

went for the first flight and I am satisfied with it, mind you I didn't go too far because of the wind on the coast was very strong but the MP handle it well,  I was only about 3 metres off the ground any more than that  would have been nerve racking,  but so far no complaints,  will definitely fly more when the winds settles down.

Do we need to update each battery?

Same thing here.  Updated last night, ran three batteries this morning.  CHECK YOUR SETTINGS of course.  Everything changes.  I fly with a Note 5 samsung and Android.  App version 4.2.20.  The only bug I had while flying was I did a precision take off and a bit later, tested RTH.  The drone turned, headed home, oriented, came down.... about 10' away from the pad.  Overrode it, and landed.  Changed battery, flew it out about 500', hit RTH and it landed dead center on the pad.  
Video had an occasional tiny stutter, not enough to really notice unless you were looking for it.  Point of interest and C1 and C2 no problems.  I didn't check all my video settings until after the first battery.  Video had changed to MOV, 4K, 24 fps.
The fastest I've gotten my drone up to in Sport Mode has been 42.7 mph.  I have noticed with previous updates, my max speed dropped to about 39 mph.  Today I hit 41.9 mph.  Much better than the past.  
Flight was rock steady and no problems.  RC did give a buzz/vibration for no apparent reason, so I'm gonna dig into the logs to see what that was.  Only did it one time.  
Oh yeah... and your picture index counter resets to start all over again.  

Folkestone Posted at 2018-7-7 08:10
Do we need to update each battery?

No battery firmware updates.  At least, nothing squawked when I was flying today.  

I updated the firmware and andiod app yesterday. Since the updates the video feed is extremely pixelated and I lost the signal completely a couple of times. It am having the same issue with both my phone and tablet.  Nothing I have tried seems to have worked.  e.

Brad Bilger Posted at 2018-7-7 08:17
Same thing here.  Updated last night, ran three batteries this morning.  CHECK YOUR SETTINGS of course.  Everything changes.  I fly with a Note 5 samsung and Android.  App version 4.2.20.  The only bug I had while flying was I did a precision take off and a bit later, tested RTH.  The drone turned, headed home, oriented, came down.... about 10' away from the pad.  Overrode it, and landed.  Changed battery, flew it out about 500', hit RTH and it landed dead center on the pad.  
Video had an occasional tiny stutter, not enough to really notice unless you were looking for it.  Point of interest and C1 and C2 no problems.  I didn't check all my video settings until after the first battery.  Video had changed to MOV, 4K, 24 fps.
The fastest I've gotten my drone up to in Sport Mode has been 42.7 mph.  I have noticed with previous updates, my max speed dropped to about 39 mph.  Today I hit 41.9 mph.  Much better than the past.  

interesting.. a buzz/vibration?   i thought mine sounded slightly different, but not very different..  slightly higher pitched.. right?   and when you rotate it changes where noise seems to come from to like dif corner of the drone.   because i think i made a similar observation on .400

Brad Bilger Posted at 2018-7-7 08:30
No battery firmware updates.  At least, nothing squawked when I was flying today.

I flew two batteries on it today.

The app froze once. Grey screen, no response from the phone so I landed her, reset the app and took off again. No problems after that.

I'm running everything in its latest form on an iPhone 6s+

Folkestone Posted at 2018-7-7 10:32
I flew two batteries on it today.

The app froze once. Grey screen, no response from the phone so I landed her, reset the app and took off again. No problems after that.

check your cable... sometimes failing cables cause screen glitches

HereForTheBeer Posted at 2018-7-7 10:13
interesting.. a buzz/vibration?   i thought mine sounded slightly different, but not very different..  slightly higher pitched.. right?   and when you rotate it changes where noise seems to come from to like dif corner of the drone.   because i think i made a similar observation on .400

I didn't notice any difference in the sound of the Drone.  The behavior was the same as usual.  The buzz/vibration was like if you get a warning message, you get the beep and the vibration.  All I seem to get was the vibration.  When I glanced down at the screen, there was no messages there.  Looking back at my log on the phone, it appears that the vibration WAS a warning message that popped up stating Class B Airspace.  Be careful.  (I get that all the time.  I'm out 13 miles out from the Restricted area. ) Like I was saying, the only real things that I noticed was all the camera settings had changed.  Resolution, Index Count, FPS, Photo Ratio...  I tried the Point of Interest and had no problems before, during or afterwards with any other button.  

But.... I'm one of the weird ones... Every firmware update, every app update on my drone or phone runs smooth as silk afterwards.  No problems at all.  

HereForTheBeer Posted at 2018-7-7 10:32
check your cable... sometimes failing cables cause screen glitches

I always a carry a couple of extra cables for that event! Didn't need a change this time and all seemed happy.

Brad Bilger Posted at 2018-7-7 10:44
I didn't notice any difference in the sound of the Drone.  The behavior was the same as usual.  The buzz/vibration was like if you get a warning message, you get the beep and the vibration.  All I seem to get was the vibration.  When I glanced down at the screen, there was no messages there.  Looking back at my log on the phone, it appears that the vibration WAS a warning message that popped up stating Class B Airspace.  Be careful.  (I get that all the time.  I'm out 13 miles out from the Restricted area. ) Like I was saying, the only real things that I noticed was all the camera settings had changed.  Resolution, Index Count, FPS, Photo Ratio...  I tried the Point of Interest and had no problems before, during or afterwards with any other button.  

But.... I'm one of the weird ones... Every firmware update, every app update on my drone or phone runs smooth as silk afterwards.  No problems at all.

oh ok...  i think maybe was just the slight breeze and my props are spinning slightly  faster than used to be. i may try to compare the speeds props are spinning at, im using the winglet gold tipped plat props on my standard mavic pro.

and for me, .300 made my controller buzz a lot more than .100  every alert just before displays on screen so for me .400 didn't really change any of that...been buzzy since .300

and yea every update resets my settings in app...refreshes dont though

Folkestone Posted at 2018-7-7 10:47
I always a carry a couple of extra cables for that event! Didn't need a change this time and all seemed happy.

oh good plan!  ya i have a few bad cables i had to toss that causes on screen freezing, blotchiness/smeariness and sometimes even shows incorrect signal values..  

i usually blame the cable first if i see smearing or blotchiness

HereForTheBeer Posted at 2018-7-7 10:58
oh good plan!  ya i have a few bad cables i had to toss that causes on screen freezing, blotchiness/smeariness and sometimes even shows incorrect signal values..  

i usually blame the cable first if i see smearing or blotchiness

The only one that really gave me any trouble was the one that DJI supplied.

I thought I had another broken cable but it turned out to be a lump of lint in the cable hole on the iPhone.

Folkestone Posted at 2018-7-7 11:03
The only one that really gave me any trouble was the one that DJI supplied.

I thought I had another broken cable but it turned out to be a lump of lint in the cable hole on the iPhone.

Don't ya just hate it when that happens???  At least, it was an easy fix... LOL