I had just downloaded the 1.14.1 map 10 years of Minecraft, opened the world and instead of showing the map I had just downloaded, it showed a blank superflat world. I tried creating a new copy of the world but I got the same results.

Replicate by,

-Go to Minecraft.net and download 10 years of Minecraft map on a Windows 10 computer.

-Go to Files then My PC, then search 10 years of Minecraft

-Minimize Files and press windows key+R

-Enter %APPDATA%\.minecraft

-In this File, press Saves

-Go back to the 10 years of Minecraft and hold left click then move it to Saves

-Open Minecraft 1.14.1

-Go into the new world