I just cannot add an Address with the API. I managed to update every other coloumn type, but not the address one.
I tried two ways:
$array['ADDRESS']['addr1'] = 'Amara Locks 12588'
...
didn't work. I got the error message:
400: The resource submitted could not be validated. For field-specific details, see the 'errors' array.
Because of this post I thought I needed to convert it to JSON. It worked for not getting any errors, but the field address stays empty in MailChimp.
Just for an example how the array looks like:
["ADDRESS"]=>
string(124) "{"country":"DE","addr1":"Amara Locks 12588","addr2":"Second Floor","state":"North Dakota","city":"East Kadin","zip":"33183"}"