I agree with barszap, I think there are issues with notifications and feds actually appearing. Friends that always sent 3 feds have started tapping 1-2 houses in my town. I also notice that when I visit towns with "max feds" I get a lot of lag. I suspect that when my town has a lot of lag I am actually maxed but not receiving notification or a false message that my town has been cleared (most I've ever tapped is 9 feds in my town).
Sometimes synching helps "missing" feds appear, sometimes exiting app does as well. However there are times when nothing I do will help me find the feds.
