Think I found a bug, maybe. Everything disappeared from the world. Trees, buildings, grass, weeds, crops, folk, everything but the player. Weeds eventually started growing on soil, but otherwise the world was empty. This happened in 7.1 (screen shot is from 8.1, but it looks the same).
I was not sure I should report this because I did edit my save. I changed the names of the bots but nothing else. It is possible I made a mistake, but not likely. The edited save worked for a few days, and I have versions of the save that are still working.
Me and the Weeds