How to update the country filed for customer

[testAppKiss]

Hi, 

I am trying to create a two step registration process.
Step 1 - Normal customer registration which accepts Firstname, email and password. 
Step 2 - Custom registration form to get the address and company details.

For step 2 , a custom form will be created then on submit, it will make a ajax call which updates the details against the particular customer in DB. 

Now, I have all my address fields are updated but the country alone is not updated. 
Can anyone suggest me why this would be ? 
sample json code structure for customer 

 {
            "id": 7532313805142,
            "email": "jamestest@gmail.com",
            "accepts_marketing": true,
            "created_at": "2023-12-28T17:50:33+01:00",
            "updated_at": "2023-12-28T17:51:26+01:00",
            "first_name": "James",
            "last_name": "Harry",
            "orders_count": 0,
            "state": "enabled",
            "total_spent": "0.00",
            "last_order_id": null,
            "note": null,
            "verified_email": false,
            "multipass_identifier": null,
            "tax_exempt": true,
            "tags": "BE 12345",
            "last_order_name": null,
            "currency": "EUR",
            "phone": null,
            "addresses": [
                {
                    "id": 9986085585238,
                    "customer_id": 7532313805142,
                    "first_name": "James",
                    "last_name": "Harry",
                    "company": "ABC Corp",
                    "address1": "123 Main Street",
                    "address2": "Apartment 456",
                    "city": "Bruges",
                    "province": null,
                    "country": "Belgium",
                    "zip": "1234",
                    "phone": "123-456-7890",
                    "name": "James Harry",
                    "province_code": null,
                    "country_code": "BE",
                    "country_name": "Belgium",
                    "default": true
                }
            ],
            "accepts_marketing_updated_at": "2023-12-28T17:50:33+01:00",
            "marketing_opt_in_level": "single_opt_in",
            "tax_exemptions": [],
            "email_marketing_consent": {
                "state": "subscribed",
                "opt_in_level": "single_opt_in",
                "consent_updated_at": "2023-12-28T17:50:33+01:00"
            },
            "sms_marketing_consent": null,
            "admin_graphql_api_id": "gid://shopify/Customer/7532313805142",
            "default_address": {
                "id": 9986085585238,
                "customer_id": 7532313805142,
                "first_name": "James",
                "last_name": "Harry",
                "company": "ABC Corp",
                "address1": "123 Main Street",
                "address2": "Apartment 456",
                "city": "Bruges",
                "province": null,
                "country": "Belgium",
                "zip": "1234",
                "phone": "123-456-7890",
                "name": "James Harry",
                "province_code": null,
                "country_code": "BE",
                "country_name": "Belgium",
                "default": true
            }
        }

Here in my frontend request I am sending country as France but still this is not updated.

address.php?address1=123 Main Street&address2=Appartment 123&city=Bruges&country=France&company=ABCCorp&zip=12345&phone=123546&tags=BE+1234567&customerId=7532313805142

Sample php code 

$customer_address1 = $_GET['address1'];
$customer_address2 = $_GET['address2'];
$customer_city = $_GET['city'];
$customer_country = $_GET['country'];
$customer_company = $_GET['company'];
$customer_phone = $_GET['phone'];
$customer_zip =$_GET['zip'];
$customer_tags =$_GET['tags'];
$data = json_decode($response, true)

    // Check if the customer is found
    if (isset($data['customer'])) {
        $selectedCustomer = $data['customer'];

        // Update the address, country, and company fields
        $selectedCustomer['addresses'][0]['address1'] = $customer_address1; 
        $selectedCustomer['addresses'][0]['address2'] = $customer_address2; 
        $selectedCustomer['addresses'][0]['city'] = $customer_city; 
        $selectedCustomer['addresses'][0]['country'] = $customer_country; 
        $selectedCustomer['addresses'][0]['company'] = $customer_company; 
        $selectedCustomer['addresses'][0]['phone'] = $customer_phone; 
        $selectedCustomer['addresses'][0]['zip'] = $customer_zip;
        $selectedCustomer['tags'] = $customer_tags;

        $updateUrl = "https://$api_key:$password@$shop_url/admin/api/2023-10/customers/{$selectedCustomer['id']}.json";
        $options = [
            'http' => [
                'method' => 'PUT',
                'header' => 'Content-Type: application/json',
                'content' => json_encode(['customer' => $selectedCustomer]),
            ],
        ];

        $context = stream_context_create($options);
        $updateResponse = file_get_contents($updateUrl, false, $context);

Can I know why my country is not updated ?