Ok so i have watched the battles each time the fighters never launch I have had the battle ship with line of sight and without and have no idea why i even researched those fighter bays now since they seem to be broken
They take time to launch so the ship has to live long enough.
Also lots of replay bugs.
If you targeted a pirate fleet then the low armor of pirates will mean they are all most likely dead to your fleets faster firing weapons before fighters launch. This is a drawback of their very simplistic implementation currently.
Fighters are sorta broken but if you understand them they are great for killing Dreads
Might as well not even build dreads for anything other than the flagship level