Alright, I'm pretty sure this is a bug.  I can include more information if needed.

I'm on the fourth mission of the Dark Avatar campaign.  A dread lord battleship comes and starts attacking my homeworlds.  I get together a small fleet of 5 small ships to go attack him... Well, he takes the bait and comes right next to my group.  The next turn I attack but only 4 of my ships attack, the 5th does not.  He, not surprisingly, destroys all of my ships in his attack round.  I'm surprised and frustrated because now he only has 1 HP.  So, I take another ship that was not in the group and attack to finish him off.  Not only do I not destroy the battleship, but, after that battle, he has 17 HP!

FYI, I do have all the current updates installed.