If you have a fleet with reinforcemed bulkheads that gets wiped (all but a few) there seems to be a cap (approximately 20?) that can be recovered no matter what. I'm not sure if this is a bug or a design oversight or intentional but I don't think it's good: here's why
Reinforced bulkhead allows you to fight dangerous opponents (For instance, remnants) that potentially could annihilate you without fear of being totally screwed after the battle even if you win. Reinforced bulkhead is a good mechanic because it allows you to trade tactical utility (those OP would be better spent in just about anything) for strategic/economic peace of mind. It synergies very well with industrial style of play because you basically just throw a kitchen sink of garbage at the enemy (captured pirate stuff) and bury them, then pick up your junk after the battle and keep going. This strategy is risky since you are encouraged to take risks that might lead to a fleet wipe (total loss) and its also costly cause you have to haul around a lot of support ships to carry supplies and fuel to repair a broken fleet in the far reaches. Not to mention it only provides insurance for ONE battle, if there are other enemy fleets you are in trouble. So it's a good balanced fun promoting strategy - except its (apparently???) gimped beyond a certain number of arbitrary losses. It doesn't make any sense and I hope its just a bug, cause if it's a design desciion its really bad. This game is already punishingly difficult to manage logistics and fleet composition and stuff and the reinforced fleet allows you to have a lot of fun without worrying about perma losing ships.
To give an exampple, I recently fought a battle using one super capital + 25 ish odd junk ships like pirate falcons and ventures. Basically the junk was there to tarpit the remnants while the capital moved in to crush vulnerable ones and CR degrade the remnants to death. IT worked, I lost everything but the capital, but then I didnt get like five ships back, even though these ships are speicifically designed for this (they have reinforced and blast doors all). Some of them even had built in mods, so those story points are now gone permanately, again even though my whole fleet is designed speficially to avoid this nonsense. URGH. Im not sure whats going on, but I hope you will look into this and think about it if its a design desicion.