I just finished playing through Tobruk, and encountered some bugs, both minor and major. I swapped out my Vulcans for Disruptors, for one. Then when the transport tried to dock with that derelict corvette, I disabled rather than destroyed it, disarmed it, and left it alone. Then, later on after all of the action was over with, I went back and finished it off, prompting both the 'lets get over to the station' messages and and the directive. You might want to nullify these if all the action is over. Also, after disabling the transport, and before closing on the station to trigger the attack sequence, I bypassed it and attacked the enemy capital ships. I disarmed, disabled, and destroyed the flak cruiser, prompting the 'lets press on to the corvette' message to be played. Then I moved in the corvette and knocked out all its weapons and engines. I should note, that while the cruiser opened fire on me, the corvette didn't. Then I returned to the station and triggered the attack sequence. After the main action was done, there was the 'knock out the beams on the corvette' message, and what's supposed to be the corvette and cruiser's advance on the station. Unfortunately, with the cruiser destroyed, and the corvette disabled, it was impossible for the mission to proceed. I then restarted the mission, and did everything the same, except I only knocked out one of the corvette's engines. I'd hoped to wait until it got within weapons range of the station before disabling it completely, so the station's heavy guns could do what my meager Proms couldn't, but alas it jumped away before that could happen. Also, once all enemies (except that one disabled transport) were destroyed, the derelict corvette jumped away for some reason, and furthermore, it didn't show up in the event log as having departed. With no-one aboard, it shouldn't be able to retreat.
So, I'd suggest tightening up the messages regarding the transport, so they don't trigger if the action is over. Second, you may want to add a second trigger to the attack sequence, should the player get too close to the enemy capital ships. I'd also suggest leaving at least the corvette's defensive turrets active to begin with, and using a guardian-threshold on its engines so they can't be knocked out... assuming there's no contingency in the mission for its destruction. Lastly, find out what's triggering that derelict corvette to depart.
Thanks.