I got Trusted Places working from home on both my N4 and N6 by following these steps. (neither were working with my home address)
First, turn location mode to "battery saving". (shuts off GPS radio)
Then, Security -> Smart Lock -> Trusted Places -> Add -> Click CANCEL for "Improve location accuracy?" to keep GPS off
Drag the red pointer just outside the inner blue circle until "Select this location" reads latitude and longitude coordinates. In my case, my front lawn worked for this.
Pick that location, call it whatever you want, and Trusted Places from your front lawn (and home) should work now. Even when you turn high accuracy GPS location back on.