I don't know how to fix but I've noticed that behavior both in Star Salvage and in vanilla games. I first noticed that a few Empyrion updates ago. I'd guess it was an unintended consequence of some other change/fix that was made to the base game. Sure is annoying though. You can usually get a couple turrets to fire if you get just the right angle on the target so that both turrets are about the same distance away. But having a whole bank of turrets doesn't seem to be an advantage right now.