Realms/Server appears to be reverting to previous versions of a world. Last identified incident was 24-July-2017, after several login/lag errors (bugs already appear to be logged in relation to this), played on a realm for around 3 hours, logged out, came back an hour or so later to find the Realm had been reset to its state some 4-5 hours previous. This is the second such incident in about a month.