hello,
I still have this altitude drops problem with my P4. Impossible to have a very steady shooting at the beginning and also and the end of the movement.Specially in a windy time and "bad" weather. I don't have the very last update but i did every calibration and updates possible after the v01.01.0411 firmware. Do you think this update is going to resolve my problem? to be precise, on my video i something step on the gas because i was afraid ti crash my aircraft...you will see when for sure.
Also, P4 is not recognize on my macbookpro with macOS 10.8.5?
thank you.

Had the same problem, the firmware released a few days ago has fixed it
2016.7.12
Overview:
 All-in-One firmware version updated to: v1.2.503
What’s New:
 Reduced the occurrence of sudden altitude drop and mitigated the drop range during flight.
 Fixed DNG files displaying issue in HDR mode.

thank you for your answer. I hope so... i will do the upgrade. thank you

Hello sguisset, please try to update your drone to the latest firmware v1.2.503. Mac OSX 10.10 or later is recommended when you want to do the update via DJI Assistant 2. But you can also do the upgrade with DJI Go app.

hello DJI-Paladin,
thank you for your answer. I hope the last update will resolve this problem because it's impossible to start a good shooting, i mean from the beginning to the end of the movement...and i hope my P4 will be better and better in the future.
Thank you for your entire message.