Downloaded maps stay on Building Terrain

When I am downloading some maps made by someone, and import it to MCPE, and play it, it doesn't show up the world, instead it stays on Building Terrain screen, which it wouldn't finish, and some of the maps work, but with missing terrains, I tried again but nothing.

Steps to reproduce;
1. Download any map on the internet
2. Import it to mcpe (/mnt/sdcard/games/com.mojang/minecraftWorlds) (Folder extract)
3. Go to MCPE, it should appear the map on the world selection screen
4. Click on the map
5. Wait until the building terrain screen wouldn't finish.