My guild needed some of the Linseed Oil from the Conservation of Resources achievement; so four of us got in a party, made sure we were all on the “Torn from the Sky” story quest, and entered together.
We took the “Fortify Defenses” route and made sure to protect the turret during the night. After the end fight the turret remained at half health, but nobody got the achievement.
We fulfilled the “You didn’t lose the turret during the night attack” requirement. Whats up?