Google Analytics unique purchases suddenly stopped working

For some reason reporting of unique purchases has stopped working in google analytics for the past few days.

It has been working for over 6 months without a flaw, but all of a sudden (it seems since the last iphone app update) it has stopped recording unique purchases. I didn't modify anything related to the GA code since the last iphone release. I am viewing the unique purchases using the "Custom Reporting" in google analytics, using the "Unique Purchases" metric, and "Day" dimension.

The analytics calls are integrated from an iphone app, and I make the ecommerce calls addTransaction , addItem and trackTransactions - and they all return without a error when i debug through the iphone simulator.

I am following this document as reference: http://code.google.com/apis/analytics/docs/mobile/ios.html

Im not doing anything different to what the docos are saying.

Any assistance as to how i can figure out what is going wrong would be greatly appreciated.

thanks.

martin