It's not explicitly stated but it seems that this island was not charted because the area it was in had previously been full of icebergs.
> On the satellite images analysed, the island could hardly be distinguished from the numerous icebergs drifting around in the immediate vicinity due to its ice cover.
> the scientists and ship's crew were surprised by the sudden appearance of an island that had previously only been marked as a danger zone on the available nautical charts.
There is definitely cursed pirates treasure on that island
> On the satellite images analysed, the island could hardly be distinguished from the numerous icebergs drifting around in the immediate vicinity due to its ice cover.
Generally somewhere around here:
https://maps.app.goo.gl/wy1PNDWcvP7h9d4j7?g_st=ic
I notice that this area isn’t fully imaged. Just around the known existing islands.
There is definitely cursed pirates treasure on that island
Would be interesting if they find more info on the satellite images they are examining.