This has been in an issue for a while (all past versions), I've seen a similar bug report (mcpe-2946) for 6 inch 1080p devices but it does the same on the nexus 10 as well.

The inv bar is way too small and is often missed and the home or multi button is hit, when inv is up the top row is above the viewable area. Scaling is just off in general as the screenshots show.

I would suggest full screen with the pause button (or swipe down like most android game use to get the top/bottom buttons) like is available in the iOS version instead of relying on the ever present back button..