Sadly I cannot give too much details of what happened with this bug as I did not realise for a few minutes after it must have happened. I had a fleet of about five or six TEC cap ships around a repair station before sending them to intercept a small enemy fleet. After sending this order I had focused on something else so I didn't actually see the movement. When I went to check the fleet's progress I noticed that when looking at the icons on the left of the screen the planet they had left still had one capital ship there and sure enough the moving fleet was missing a Kol Battleship. However when actually looking around the gravity well the ship was not there so I double clicked the icon and found myself staring into empty space some undeterminable distance away from any system and the ship was not actually in sight. Unfortunately there isn't a great deal else I can say to describe the situation but hopefully it was just a one off.