We made a purchase - a real product using a test account, we did not use one of the android test ids. The Google Popup box appeared as normal, we entered our password as normal, and got the "this is a test purchase you will not be charged etc" message. When we pressed ok, the application crashed and stopped responding with this error dialog:
"Sorry. The application Game-Name(process com.HappyBuddhaGamesCWW.PKG3) has stopped unexpectedly. Try again."
So the next time I run the same app, it crashes with the same error almost immediately upon starting the app. If I CHANGE the package name and resubmit to a new APK slot on Google Play Developer, then the app runs just fine as long as I don't press the IAP button to purchase again.
Another answered question suggested this was a licensing issue, but I do not use Eclipse, I use Game Maker Studio. I too suspect this is some kind of licensing thing, but I don't know exactly where to look.
Any help, pointers or suggestions would be GREATLY appreciated.
The problem was my Google Play License. It were munged in my GameMaker Global Game Settings/In App Purchases/Google Play Public Key window. When I replaced it properly, with no spaces, all was well.