Chests delete all items stored after loading a new world

The chests don't save my stored items as they should do. They only keep it until I leave the game then they just dissapear and the chest is empty once again. Same applies for big chests or minecart chests.

Steps to reproduce (lol mojang):
1: Make a chest
2: Put it somewhere and keep some dumb blocks there (such as dirt)
3: Leave the game then load it once again
4: Open the chest and notice the dirt blocks are gone