Lost progress (yet again)

Yet again, game updates have lost world progress. Several weeks ago, returning to the game after an update saw one of my oldest worlds - almost 6 years old, had been reverted and lost almost a year's worth of progress.

 

Today, 1.6.0 update has yet again lost progress. This time, entirely deleting not one, but two worlds (one backup of the other) entirely. These worlds were created just under 2 weeks ago.

 

I'm getting pretty tired of this. I don't feel I can safely start a large project without the game deleting it. I'd like to know what's going on.