Bedrock realm crashes and goes back to a previous point

Realm owned by user frickfragady. 3 users on at same time. Make 15.mins (ish) of progress, then all three users get disconnected. When we reconnect, our progress is lost and we're back to that point again. Happened twice.

Client version is 1.16.10

Wild guesses ; is the realm attempting to save a checkpoint of progress and crashing? (maybe underlying data store has problems?)