In the third scenario of The Hard Ruler campaign there is a bug in the west corner of the map. There is a black zone who stay black even with unit in or just next to the zone.
I send a ship here but he disappear, he even deselected himself. Even with double clicking from a same ship selected this ship for a glitch but deselected him. I try with assigning in a group but clicking on the group shortcut did nothing except the glitch.
Also I send a ship to travel across this black zone he disappear and deselected when entering in the black and then he reappear and reselected himself when he exit from the black zone.
Then I made a test I send catapult galleon n the black and enter the two cheat code marco and polo an order them to attack ground and then I renter the cheat code marco and polo and see the ship to continue attacking ground.
Here a screenshot of the black zone. In the red circle the projectile of the tree catapult galleon in the black zone.
Here the same zone with the cheatcode marco and polo
I think there is some scenario editor object who hide the zone.