Originally posted by Nameless:

Multiplayer ?

No Single Player.

Originally posted by Maiskolben:

In singleplayer you need to be on the original World-Seed you've created once. It#s a number shown in your serverlist overview. Sounds like you are on a different world.

Nope Its Was The Same World....

Originally posted by Mharr:

Was the flat land something dug by a player? Are the coastlines and biomes still in the same places you remember?

There was a small area that i had flattened but not near the area affected.

Images: https://imgur.com/a/sKIfSdR

Originally posted by Dr Vexler gorbeinstein:

It sounds like you're in the wrong world/ server. Parts of the map that already have been explored should not change when the game updates .

Not possible to be in the wrong server or world as previously stated its Single Player and the ONLY world i had at the time. No other active worlds.