To make this nice and simple, pause the game, enable the console (
) and type GiveAllExplorerNotes. After this make sure you click on the Admin Command button next to the text box.
The game may freeze for quite a while, but leave it running and eventually it will sort itself out and your achievement(s) will unlock.
I have done this today, so I can confirm it currently works.
Edit: YODA12320 has informed me that it works on the Windows version as long as your game is up to date.
Edit 2: From PsiScream - “I originally had the same issue as jotg05. If Perfect Explorer is your last one and it's not popping, try this. Quit ARK, go to manage game and addons, scroll down to saved data, highlight and click your profile - choose 'delete everywhere'. Beware - this will delete all your saved data locally and in the cloud for this game. Then launch ARK, scroll to the very top of the middle column, and select 'delete all singleplayer data' and then 'delete dedicated server data'. Then launch the Island and use the code. This finally worked for me after 3 previous failed attempts.“ - Hope this helps some of you who haven’t managed to unlock it.