The Nightwatch campaign quest appears to have a bug of some kind. I found this post which helped me get around the issue.
There are two types of propaganda to pick up: scrolls on the ground and flyers on the wall. I only picked up the scrolls on the ground, but once I picked up a flyer (putting me at 9 since I had already picked up 8 scrolls), the quest progressed and allowed me to turn in.