When trying to find out why a particular ad campaign isn’t being delivered as you thought it should, the DFP documentation indicates that you should apply “google_debug” to the URL and a new window show pop up with the debug information. After digging through documentation and searching Google for a couple of hours without getting this to work, I finally found the relevant part of the DFP documentation.
Here’s the kicker: in the new, improved ad handler (gpt.js) you’ll have to append “google_console=1” in your URL, then press CTRL+F10 to launch the debug console. No google_debug, no google_pubconsole, just google_console and CTRL+F10.
Hopefully this will help someone trying to find out by searching for relevant terms.