Cannot export CUSTOM donor data.

[jobst]

This question/problem is related to EXPORTING custom fields collected in donation forms (donor AND donation meta).
Doing this using code.

Reason for not using Form Manager:
Poltical donations in Australia are littered with laws (and dangers/litigations).
We need to be careful how we present the donations and what we require as data, using form manager this can be tricky to achieve.

My aim:
To provide custom fields for donations AND donors to have them added to the database, displayed in the donations/donor listings on the website AND exported to CSV.

One goal achieved:
I have my goal achieved for donations, I present the questions in the forms, store the recevied data in the DB and present the data in the donations listing (using the example in https://github.com/impress-org/givewp-snippet-library/blob/master/form-customizations/custom-fields-plugin.php) and can export them to CSV.

My problem:
While I can present the donor related questions in the donation forms, store them in the database (can see data using phpMyAdmin), present them in the website listing - I cannot export the DONOR data to CSV.

This might be a bug or me doing it incorrectly, your help is appreciated.

My code and how I am doing it:
I followed the example provided in
https://github.com/impress-org/givewp-snippet-library/blob/master/donors/add-donor-meta.php
I have more fields, but for this report I ONLY show one.
Presenting the field, it shows up and I can type into the field.

add_action( 'give_donation_form_after_email', 'vot_give_add_donor_custom_form_fields' );
function vot_give_add_donor_custom_form_fields($form_id)
{
  ?>
  <p id="give-wrap" class="form-row form-row-wide">
   <label class="give-label" for="give-phone">Phone<span class="give-required-indicator">*</span>
    <span class="give-tooltip hint--top hint--medium hint--bounce" aria-label="We may need to contact you as this is a political donation." rel="tooltip"><i class="give-icon give-icon-qu
estion"></i></span>
   </label>
   <input class="give-input required" type="text" autocomplete="phone" placeholder="Phone" name="give_phone" id="give-phone"
          value="<?php isset( $_POST['give_phone'] ) ? give_clean( $_POST['give_phone'] ) : ''; ?>"
          aria-required="true">
  </p>
  <?php
}

Making sure it shows an error if not filled, this works too:

// validate our custom fields for givewp
add_filter( 'give_donation_form_required_fields', 'vot_give_validate_custom_fields', 10, 2 );
function vot_give_validate_custom_fields( $required_fields, $form_id )
{
  // phone is required at all times.
  $required_fields['give_phone'] = array(
    'error_id'      => 'invalid_phone',
    'error_message' => __( 'Please enter phone number, a phone number is required.', 'give' ),
    );
  // return to caller
  return $required_fields;
} 

Add field to database, this works too as I can see it properly set in the DB using phpMyAdmin.

add_action( 'give_insert_payment', 'vot_give_donations_save_custom_fields' );
function vot_give_donations_save_custom_fields( $payment_id )
{
  // phone number
  if( isset( $_POST['give_phone'] ) )
  {
    $donor_id      = give_get_payment_donor_id($payment_id);
    $tmp           = give_clean($_POST['give_phone']);
    $phone_numbers = Give()->donor_meta->get_meta($donor_id,'_give_phone');
    // Add phone number to donor meta only if not exist.
    if(!in_array($tmp,$phone_numbers,true))
    {
      Give()->donor_meta->add_meta($donor_id,'_give_phone',$tmp);
    }
    // Save phone number to donation meta.
    Give()->payment_meta->update_meta( $payment_id,'_give_phone',$tmp);
  }
}

Show donor information in the donor listing, this works too

add_action('give_donor_before_address','vot_give_show_donor_custom_info');
function vot_give_show_donor_custom_info( $donor )
{
  $phone_numbers = $donor->get_meta('_give_phone',false);
  ?>
  <div class="donor-section clear">
   <h3><?php esc_html_e('Phone Numbers','give');?></h3>
   <div class="postbox">
    <div class="inside">
    <?php
    if(empty($phone_numbers))
    {
      echo "<p>This donor does not have any phone number saved.</p>";
    }
    else
    {
      foreach($phone_numbers as $item)
        echo "<p>".$item."</p>";
    }
    ?>
    </div>
   </div>
  </div>
  <?php
}

Show check boxes in the 'EXPORT DONORS' section inside the TOOLS tab.
This works, I can see the check box

add_filter( 'give_export_donors_get_default_columns', 'vot_give_add_custom_column_to_export_donor' );
function vot_give_add_custom_column_to_export_donor($default_columns)
{
  error_log("------------------------ exporting donor columns");
  $default_columns['phone_number']   = esc_html__('Phone Number', 'give' );
  return $default_columns;
}

This is the part that does NOT work.
The data is never exported, also the error message never shows up in the PHP log.

add_filter('give_export_set_donor_data','vot_give_export_set_custom_donor_data',10,2);
function vot_give_export_set_custom_donor_data($data,$donor)
{
  error_log("------------------------ exporting donor data");
  // phone
  $phone_number = Give()->donor_meta->get_meta( $donor->id,'_give_phone',true);
  $data['phone_number'] = !empty( $phone_number ) ? $phone_number : '- N/A - ';
  // return to caller
  return $data;
}

Not sure what the problem is, I followed the guidelines provided in
https://github.com/impress-org/givewp-snippet-library/blob/master/donors/add-donor-meta.php