OK. So several months ago I was playing around and got the test ads to show, but when I tried to use my ads they wouldn't show.
I got busy and left it alone.
Now. When i try again, following whatever I can find in the forums, I can't even get the test ads to show.
Attached is what I think is the code required to show the test ads. If someone can take a look at point out what I missed I'll take another look when I get a chance.
After one of the updates, an option appeared in my settings.
Under Google is an option for Ads, and under that is an option to Enable debug logging for ads. This was turned on by default and it's the culprit. Turning that off fixes the issue of me not being able to serve ads on this phone.