Primary Postal Address

I've had a number of transactions over the past couple of weeks where the buyer has sent a message saying they are unable to pay and have received a note from eBay saying the 'seller won't send the item to your primary postal address'.

 

All of our listings are available Australia wide. I contacted eBay and they could see nothing wrong with the checkout process or postage policy on our listings.

 

Has anyone else has this problem and found a solution?