I've got a squadron of four ships under missile attack. Every 25 seconds a new wave of missiles are detected. All the ships are of the same class, their beam weapons all have a 5 second recharge time and plenty of power and all the fire controls have the same setting of Final Defensive Fire.
What is confusing me is the inconsistency of their fire. Against the first wave of missiles all the ships will fire, but then only two fire against the wave after, then all four will fire against the next wave, then three ships, then just one. There's no obvious pattern to which fires and which doesn't. It's not combat damage (the armour is dented but no internal damage on any of the ships) and they are all identical so I don't understand why some fire and others don't.
Is it a bug or this just something I have to allow for when designing my PD ships?