Minecraft Structure Loading

Issues loading Minecraft game in new release. I made a backup of the world, loaded in Latest Release from 19w45b, expected issues. But my structures were reverted back to its original state. I had spent two days building a castle, but when I opened it, the area was back to what it was before I started constructing. 

I thought maybe my initial one hadn't saved, but then I noticed I had retained all my levels and my inventory that I had upon closing the program. There also now seemed to be two pools of lava in there area where there previously was not lava at all.