Hello. I'm having trouble with the secondary objective "Halt the spread of the gas." I wouldn't have even known this quest was available if I hadn't paused the game at one point, and noticed it in the list. There are no markers on my map, and nothing in game has been said about it. I looked up some information online, and found I had to kill the mutated individuals around valves then interact with the valve to complete it. I had a rough idea what valves it was talking about, but even after killing everyone everywhere I am unable to interact with them. Looking up a video is looks like you're supposed to have a checklist including all the valves on it, but I only have one that says. "Serve Gaia". Can anyone provide any guidance on something I'm missing or any way to fix this? I'd rather not leave the area without completing it.