Randomly lose progress when in multiplayer world

When playing in a multiplayer game, those who are not hosting occasionally lose entire chunks of their progress in the game. For example, my daughter just lost her house with all the work she put into it and all of the posessions she had stored inside. There was no disconnect, she just walked away from it while in the game and when she returned everything was gone. We are playing on iPhones 4s and 5s, old world types because the person hosting has an iPhone 4. Before this only used to happen occasionally when the host disconnected us. Thanks.