Indexing broken when using custom field in repeater

Hi there, thanks for some awesome tools.

I have made a custom field class for a Widget I’m building. The custom field resides in a plugin based on this sample code: https://github.com/siteorigin/so-dev-examples/blob/develop/extend-widgets-bundle/custom-fields/better-text.class.php. I have followed your documentation and I got the field working as it should, except when I put it inside a repeater. When I put it inside a repeater the indexing of the name-field seems to be incorrect. Instead of a number I get a variable that looks like #products# where products is the name of my repeater. Like so:

widgets[c60][products][#products#][start-date]

What can possibly be the reason for this?

My Custom Field class:

class My_Custom_Date_Time_Picker extends SiteOrigin_Widget_Field_Base {
  
  protected function render_field( $value, $instance ) {
    
    ?>
    <input 
    type="date" 
    id="<?php echo $this->element_id ?>" 
    name="<?php echo $this->element_name ?>"
    value="<?php echo esc_attr( $value ); ?>"
    />
    <?php
  }

  protected function sanitize_field_input( $value, $instance ) {
    $sanitized_value = sanitize_text_field( $value );
    return $sanitized_value;
  }

}

My Widget code

class TestWidget extends SiteOrigin_Widget {
  function __construct() {
    //Here you can do any preparation required before calling the parent constructor, such as including additional files or initializing variables.

    //Call the parent constructor with the required arguments.
    parent::__construct(
        // The unique id for your widget.
        'test',
        

        // The name of the widget for display purposes.
        __('Test', 'jimbo'),

        // The $widget_options array, which is passed through to WP_Widget.
        // It has a couple of extras like the optional help URL, which should link to your sites help or support page.
        array(
          'description' => __('A simple test', 'jimbo'),
        ),

        //The $control_options array, which is passed through to WP_Widget
        array(
        ),

        //The $form_options array, which describes the form fields used to configure SiteOrigin widgets. We'll explain these in more detail later.
        array(
          'products' => array(
            'type' => 'repeater',
            'label' => __( 'Products', 'jimbo' ),
            'item_name'  => __( 'Product (article number)', 'jimbo' ),
            'fields' => array(
              'start-date' => array(
                'type' => 'date-time-picker',
                'label' => __( 'Choose a start date', 'jimbo' )
              )
            )
          )
        ),

        //The $base_folder path string.
        plugin_dir_path(__FILE__)
    );
}

  function get_template_name($instance) {
    return 'test-template';
  }

  function get_style_name($instance) {
    return '';
  }
}

siteorigin_widget_register('test', __FILE__, 'TestWidget');