Have you tried to publish your app and then unpublish / deactivate it?
No, I did not.
Things have changed since I last used my development account. Now you can upload your Apk for Alpha, Beta, or Published. I would assume that as I uploaded it for Alpha testing it would be just the same as uploading it as published but not actually putting it up on google play. For Alpha testing you need to create a Google+ community group and get users on it that will do testing for you. From there they will get a link to download your APK.
I have also deleted the APK from the developer account and created a new project just to get a new key, changed the key in my code to match, and reuploaded the APK back to the account. Still same error. I don't have a good idea of what could actually generate a Not_market_managed error.
From what I have read it was something with the versions numbers not being equal between the uploaded APK and the one installed on actually devices. My versions numbers are equal. Also, I am not clear as whether I should increment version numbers everytime I upload an updated APK to the development account. Can't I always keep my version number as 1 on the APK I upload and the devices I install it to? This problem does not appear to be anything related with B4A just probably google and maybe something I'm not doing right with the process.