I am having trouble collecting SMS consent with a legacy form using the API documentation for reference.

This previously posted question (Collect SMS consent with legacy form) highlights the same issues I am currently facing, though the provided answers does not seem to be the solution in this case:

1. The phone number entered is a valid US number
2. Double-opt-in is disabled for the list 
3. The account does have SMS set up and enabled.

Here is the script for reference: 

let klaviyoSubscribeURL = "https://manage.kmail-lists.com/ajax/subscriptions/subscribe";

						const data = {
							g: "VXXXXS",
							'$fields': '$source,$email,$consent_method,$consent_form_id,$consent_form_version,phone_number,sms_consent,$consent',
							'$list_fields': '',
							'$timezone_offset': Math.abs(new Date().getTimezoneOffset() / 60),
							'$source': '$embed',
							'$email': email,
							'$consent_method': 'Klaviyo Form',
							'$consent_form_id': formId,
							'$consent_form_version': 524456,
              'phone_number' : phone,
              '$consent' : s'sms'],
              'sms_consent': true
						};

						fetch(klaviyoSubscribeURL, {
							"method": "POST",
							"mode": "cors",
							"credentials": "omit",
							"headers": {
								"access-control-allow-headers": "*",
								"content-type": "application/x-www-form-urlencoded; charset=utf-8"
							},
							"referrer": location.href,
							"referrerPolicy": "no-referrer-when-downgrade",
							"body": Object.keys(data).map(key => `${encodeURIComponent(key)}=${encodeURIComponent(dataekey])}`).join('&')
						})
							.then(res => res.json(), (res) => {
								// console.log(res);

								return res.json();
							})
							.then(data => {
								if (data.success) {
									heading.html(headingSuccess);
									$(this).hide();
									errorsBlock.hide();
									subheading.html(subheadingSuccessEmail);
									emailInput.val("");
									emailInput.parent().removeClass("input-group--label-shifted");
								}
							})

When I export the the profile data, it seems to be missing the sms_consent data object:

{
  "object": "person",
  "id": "01XXXXXXXXXXXXXXXXXXXXN672",
  "$address1": "",
  "$address2": "",
  "$city": "",
  "$country": "",
  "$latitude": "",
  "$longitude": "",
  "$region": "",
  "$zip": "",
  "$title": "",
  "$email": "sXXXXXXX6@gmail.com",
  "$organization": "",
  "$first_name": "",
  "$last_name": "",
  "$phone_number": "(310) XXX XXX6",
  "$timezone": "",
  "$id": "",
  "$source": "$embed",
  "$consent": o
    "sms"
  ],
  "$consent_timestamp": "2022-11-10T00:20:14.517Z",
  "Newsletter Signup": "2022-11-09",
  "email": "sXXXXXXX6@gmail.com",
  "first_name": "",
  "last_name": "",
  "created": "2022-11-10 00:20:15",
  "updated": "2022-11-10 00:20:44"
}

Is it still possible to collect SMS consent in this way?