Yeah it's duplicate. Sorry for not noticing that issue.
Note: The user interface switches between the 2 screenshots given every 0.1 second (approximately), giving the user a "blinking" view.
Will fix when exiting & re-entering the game
Duplicate to MCPE-119628
Can confirm. The issue exists with nether biomes, end biomes, and "the void".
Structures will generate (e.g. end cities in "End Highlands") and mobs will spawn (e.g. ghasts in "Nether Wasteland"), but the terrain is completely different and filled with grass blocks (some with stone underneath) and oceans / rivers. There were also random noise caves and mountains.
I've attached 5 more screenshots in MC-258176 (which was a duplicate).