Someone posted a fix to this here:
http://forum.dji.com/thread-45948-1-1.html

Ah, sorry.
Hopefully a DJI rep will see that it hasn't worked for everyone and address the issue.

I have te same problem here. This is so anoying!! What is DJI going to do about this? I'm using a Phantom 3 Adv., Samsung Tab4 Android 5.1.... And my Samsung smartphone gets a black screen now, no live view. What's the point? Am I supposed to get a Phantom 4 and an Apple product?!.... no way!!! (I'm portuguese, so that's why photo mode print screen says "foto").

photo mode

Video mode...

I had this problem but somehow it went away. Once it came back when I started DJI go, but then I saw the app switch back to 16:9 in front of me.

I will try to clean DJI Go app cache, then uninstall and install a clean version... But I'm not sure if it will work.

Ok there is a way to keep it in 16:9 screen. The app always assume de last image dimensions we use. So choose 16:9, then exit the app and then enter the app again. You should get the 16:9 screen, photo mode and video mode. But don't change it to 4:3, or it will block the image at 4:3 again.. You must exit the app everytime you need to change it.

For now I will keep it always 16:9.

This must be an Android thing as my iPad switches on the fly between 4:3 photos and 16:9 video without distortion.  (ie the 16:9 image crops on the top & bottom)

Unfortunately this still hasn't been fixed with the 2.7.2 update on Android.

I am having the same problem. DJI doesn't seem concerned. Litchi working perfectly.