I also have this issue. After multiple attempts, my largest world was finally converted and when I load it, new land is generated where everything else once was. Biomes changed, all blocks changed, all items gone. I thought I was on a different map, but looking at my actual minecraft map shows my old world and as I travel around it is replaced with the new generation.
Chad Harvey
I also have this issue. After multiple attempts, my largest world was finally converted and when I load it, new land is generated where everything else once was. Biomes changed, all blocks changed, all items gone. I thought I was on a different map, but looking at my actual minecraft map shows my old world and as I travel around it is replaced with the new generation.