I just played the imperial campain and it seems like bombers can't attack hulked ships.

That's too bad, I can see the advantage in using whatever means you have to deny the enemy from reclaiming a hulk.

Hello, what kind of bombers did you try to use?
It seems to work as intended on my side (only Thunderhawk squadron are disable because the target as no more troop to attack)

I had this problem with the space marines as well as with the imperial navy (both in the campain), but I will do some further testing.

I just tried some skirmish battles and it seems like all factions have this problem.

Can you precise the kind of bombers with the exact name of the skill you used please?

I have tried the imperial "Starhawk Bomber Squadron", space marine "Thunderhawk Annihilator Squadron" and the chaos "Doomfire Bomber Squadron", all against Tau merchant fleet and imperial ships.