This is identical to the issues MCPE-42226 and MC-147485 (1.13.2). We had a world that we had built up a lot over the past week and a half, but when we logged in earlier today, the only thing that was the same was the gear and inventory; the town, the buildings we had made, everything was gone. The animals we had (2 llamas) are still around, but that is the only thing that is the same.
NOTE: This is a local, singleplayer world that is shared by a few different people. The world when we last played (8/5) was fine each time we loaded it. Today (8/7), which was the next time we started to play, all of our custom structures and terrain changes were reverted to when we discovered the village.
I will add world files in the next 24-48 hours for this.