Since today when I enter an island I have no "island-blackness" anymore so I can see everything. I don't think that it is supposed should be like that. Refreshing the page, clean my cache and logging out and in didn't solve the problem.

This is an effect from the Travelling Magician, who has likely come to visit your Inn. While he is there the fog of war is cleared from the islands.

Okay thank you. I mostly don't pay much attention to the invites, that was my bad.