When riding a horse or donkey in Realms. (Not yet tested in a solo world.) If you try to jump over a river and land in the middle. Sometimes the horse will disappear, or as I like to say. Forget how to exist. I had a long travel going from my friends base at 14k, 14k to my base at -2k -1k and I had this happen to two horses and a donkey. Although I didn't really care at that point. Today however, I was traveling from my base to a different friends base a couple hundred blocks away. I was bringing my donkey which had quite a bit of good loot on it because I was planning on moving near him. When I jumped over a river only about 5 blocks long with the donkey. It disappeared taking all my loot with it. I had 3 Stacks of iron blocks and a ton of other good stuff that had taken me hours to mine taken away in just a split second. Hopefully this bug can be resolved before the next update comes.