field_data_json showing as "Array" in formfield

I have zero issues creating and updating all other fields EXCEPT "field_data_json" in the formfield API - when sending the JSON below, only "Array" shows in the field. The API says "string" for the format.

{
"active" : 1,
"field_data_json" :
{
"additionalDetails" : "Take Photo of front of the house",
"conditionMethod" : "AND",
"conditions" :
[
{
"operator" : "",
"question" : "",
"value" : ""
},
{
"operator" : "",
"question" : "",
"value" : ""
},
{
"operator" : "",
"question" : "",
"value" : ""
}
],
"fieldType" : "Photo",
"mandatory" : false
},
"form_uuid" : "b06bc5d5-7d58-4e87-9645-0b64a1b62f2b",
"name" : "Arrival Photo 1",
"sort_order" : "1"
}