There are a few shotgun messiah POI. If you can specify which one (the name at the top corner of the screen when you're standing at the POI) or describe which one it is (such as the one with the shooting gallery in back or the one with the classroom on one side of a store on the other in the front section, with a tall safe in a room between them). That will narrow it down. I've been doing quests at these for a long time, but can't say if I've done all of these POI in 1.0 yet. But I've never had a problem with them. As mentioned, it's likely that you're missing a button or key rack. You won't see the zombies until you use the button or key rack that triggers them. Floating around in god mode will not help with that.
