Okay so apparently Chartboost support tells me that their SDK does not actually show anything in the log output (v3.2). They have added it as a future feature request.
And for the ads, in the Chartboost dashboard under APPs you can set the app orientation for either landscape or portrait or both. I had orientation set to landscape but app was portrait so no ads will show when these do not match.
So it was a PEBKAC error.