So my boyfriend friends and I all play on a realms together. From what I see some things are saving but when you play for hours and get lots of progress done it does not save. In one picture you will see that there is a small area of trees chopped down but originally the mushrooms and the whole area was chopped out. In another picture you can see partial terraforming and a river was made but when we left and came back the next day the terraforming was all gone. Another incident happened when I i built up one of my towers to my castle and that disappeared along with all my quartz.