Errors in saving the world

Singleplayer
-When the / tp command is used to travel a long distance and then return to the site where it was used, what has happened in that site has not been saved.
-When you try to leave the world and crash happens, you do not keep what you have done.
-When I crashed a world did not save the progress and was left with the error that nothing is saved the world, and stays with the same MB weight.
Multiplayer
-When a player leaves the world and goes back in he has totally lost his objects (also happens when the game crashes).
-When you use the / tp command to any player and you return it to the original position you have not saved what was done there.

Device - LG X165g