Played for weeks on my brand new 1.14.2 world as seen in the only screenshot I took of my house. Second screenshot was the erased loaded chunks after loading the world in a different version of Minecraft (1.0 version). I loaded Minecraft version 1.0, and loaded up my 1.14.2 world, It asked me to create a backup of the world, I did so, upon loading into the 1.14.2 world on the 1.0 VERSION, It erased all the progress of the chunks I loaded. I thought no problem, So I went back to minecraft VERSION 1.14.2 and loaded up my normal world which I spent weeks building to a half erased world. What I mean by that is the chunks I loaded got erased completely (My house, chests, and farms). BUT the chunks I had NOT loaded in the Minecraft version SWITCH had stayed the same. So only the chunks I loaded in that old minecraft version got erased.