It turns out that previously, the API was sending back meta box data as meta_data like this:
"meta_data": [
{
"id": "2",
"key": "profile_dob",
"value": "5/11/1989"
},
{
"id": "3",
"key": "profile_gender",
"value": "Male"
}
]
Now it sends it like this:
"meta_box": {
"profile_dob": "5/11/1989",
"profile_gender": "Male"
}
Although the second way would be much easier to handle, consumers of the data need to be updated which can be painful.
I worked around it at the server side by changing the response to suit the older style but that's not ideal. I'm curious that nobody noticed this since it would likely break clients.