Embedded Chat Inlay - error setting custom field for launch-form-fields

Content

Hi,

I'm trying to use a custom field for embedded chat inlay, release 20B. I've set it up as an attribute in my config file, following the directions in the documentation:

{

    "inlays": {

      "common": {

        "attributes": {

            "launch-form-fields":["SUBJECT",  "c$person_id", "FIRST_NAME*", "LAST_NAME*"]

        },

        "strings": {

        }

      }

    }

}

The standard fields appear, however, this gives me the following error in the javascript console: "Invalid custom field 'c$person_id'"

This is a valid custom field. I've tried with a few different custom fields. I also tried removing the quotes, but of course that results in a JSON parse error.

What am I missing here?