Third-Party
I have raised this with Cashrewards and they tell me it is working correctly but not in my experience.
If I start on Cashrewards website and click Shop on the Zavvi page it takes me to the Australian site but the Firefox notifier doesn't pop up or show as being active.
The same if I manually go to the AU site - no reaction.
If I manually go to the UK site it does pop up and can be activated from there.
Cashrewards have confirmed it is meant to be the AU site, not the UK.