XBSeriesX achievement. Game version 2136

Ive been trying for a few hours now to get the “another one bites the dust” achievement but I have only found 2 of the survivor camps. I’ve taken a picture of my cartographer and charted each island 2 times(once by boat once by helicopter) to make sure I’ve been to each island. Still haven’t found it and it’s driving me crazy bc it’s the last achievement I need before I can complete the game.

Seed #46309268

Settings
haven’t changed anything

Steps
What steps, if known, can cause this issue to occur for you?
I’m not sure of anything that would cause this to happen

Extras
-Have you tried reloading your save, game or console?
Yes

-Have you tried clearing the cache of the console by shutting down for 2 mins before rebooting?
Yes

Did you by chance happen to use the Cartographer to replace any islands? It IS possible to delete the islands with Castaways on them.