well I'm on to something. I just had a thought to check the mysql database record. Of the 4 addresses in the zen_address_book table for my test account The 2 that work have a value in the 'entry_zone_id' field. The 2 that do not work have 0 for the 'entry_zone_id'.

So just need to figure out where this 'entry_zone_id' is set.

Digging to continue after lunch.