After getting the new version of Minecraft from the better together update, I keep trying to use the world conversion to get my world I have had on the Xbox one version, and every time I load it, it has replaced multiple chunks in both the overworld and the nether. Everything that I have built is replaced. With completely new chunks. You can literally see divides from chunks to chunks, weather it be from snow to desert, or mountains cut in half. In some cases, building I have created are cut in half or just completely gone depending on if the chunk was replaced or not. The file size went from 353.6MB to 174.9MB.