Device
Samsung Galaxy Tab A (SM-T350)

Description
When leaving a world, your invintory saves but if you have done any mining or building that doesn't save. (If you mined Diamonds, you would still have them in your invintory however you could go mine them again after a relog)

Steps to Reproduce
1) Join a World (I was in survival, and using an older world from previous updates)

2) make a change you can easily find

3) relog

4) you should notice that the change has been reversed