Apparent glitch in Justine DLC

[treesy]

Hi everyone. This is my first post so please be gentle, i couldn't find anywhere specifically for the Justine DLC so I'm putting this here. Maybe Custom Stories would have been better? I'm unsure!

When I get to the flooded basement area, I get the lever and open the first door and I hear the unsavory fellow spawn, I run into the hallway on the right that leads to the room that has a cogwheel on the table. I assume you need this because I've run into the left room before and i see a machine room with a spoke or two and i know the front door needs fixed (crapped my pants finding that one out on the fly). Anyway I've gotten this result twice now - I go into the cogwheel room, i creep out to the corner of the corridor, the guy is patrolling the central room like normal so i carefully creep back into the cogwheel room. Everything is fine, but as soon as i pick up the cogwheel, the "run for your life" siren plays but he never comes. If i go out into the central room, i can see that he tries to make a bee-line straight for me from where he was standing when i picked up the cogwheel, and if something is his path (like the raised floor in the center of the room) he just runs in place until i try to creep around him and then he pummels me.

I'm using steam on windows if that matters.