When ships are moving, it often happens that the fog of war is not removed properly, making holes in the path traveled.
Please make it work properly, it's really annoying.
Edit: A save file to help determine what's going on:
In this game, I play the Korath and I am allied with the Drengin.
Passing the turns and observing the movement of the Drengin ships, you will notice that the Drengin ships "jump" during their movement.
This may be the cause of the "holes" observed in the fog of war during the movement of ships (allied and opponents).