2nd player on Xbox One console placed items in chest, then left the game.  Then the first player exited the game.  Then back to the Xbox one home screen where the Minecraft application was quit.  Then the Xbox one was restarted.  This was due to the controllers disconnecting from the Xbox One.  After restarting the Xbox One, we went back into the game to find that all items that the 2nd player had placed in the chest were gone.