Changes made to environment not saving

Anytime I put down the game and stop playing for more than a a minute or two (program is still open, just not using it) any changes I made to the environment such as mining or placing objects are lost. I still retain my inventory, but anything I mined is back in the ground (as well as in my inventory) items placed disappear (do not go back to my inventory) animals revert back to the place where they were last saved (for example the horse I was riding is suddenly tied up back home again). The only changes that get saved are ones that are in my immediate vincinity at the time I stop playing (excluding animals).