My phone is the Nexus 5x

There seems to be a disconnect between when an item is added/removed from save file inventory (happens first) and when it is added/removed from save file chests (happens later) in local games. I first noticed the issue when I logged into a game that I had switched out of the night before and found a duplicated set of items in my inventory and in the chest beside me.

The item loss side of this is what makes this issue critical as it means that if you switch to another app (such as for text messaging) and Android closes the app in the background, you could permanently lose items in survival.

I can reliably recreate the issue(s) using these steps:

Item Duplication:
0) In local Minecraft Survival
1) Move items from chest to inventory
2) Enter the Android application switcher and swipe the Minecraft App to close it
3) Re-Open the Minecraft App

Expected Result: Items are either in the chest, or are in the inventory.
Actual Result: Items are in both the chest and in the inventory. (duplicated)

Item Loss:
0) In local Minecraft Survival
1) Move items from inventory to chest
2) Enter the Android application switcher and swipe the Minecraft App to close it
3) Re-Open the Minecraft App

Expected Result: Items are either in the chest, or are in the inventory.
Actual Result: Items are nowhere. (lost)

I also noticed while testing this that there is sometime some sort of corruption in the player location data in the save: when I re-opened minecraft I would sometime be teleported to a location that I had not been to for a long time. This is not completely random as often (but not always) it was the same location. It seems like you need to do more testing around how MCPE works with Android's activity lifecycle: http://developer.android.com/training/basics/activity-lifecycle/pausing.html