I forgot to press the report button, however, I didn't consider it a bug.
I'm more looking for explanation, is it possible my flagship escaped but then sunk?
Is that a random chance thing?
Also my flagship left the mission area ahead of the supply ship, is that why it disappeared?
There is supposed to be 3x 4th rates?
I'm going to test the scenario again, but I don't remember it being this difficult on my last 2 playthroughs.