Scout: Shores not popping?

[Umdytr]

I've gone over all the landmarks I can see on the map (with the ? icons) and they've changed to different symbols, but the trophy hasn't popped. Am I missing something, or is this a bug?

 

Doesn't help that there's a time limit and that the game's navigation system is awful.

[Ennlocke]

You get the trophy if you continue the main objective a bit, you'll have to unlock a shelter, the trophy popped there for me.