Exposed foorm with checkbox doesn't respect default value and $_GET parameter

I've created custom filter with checkbox exposed form in my module:

class my_module_helper_handler_filter_timetracking_children extends views_handler_filter {

  /**
   * Clear query alter
   */
  function query() {
    
  }
  
  function value_form(&$form, &$form_state) {
    $form['value'] = array(
      '#type' => 'checkbox',
      '#title' => t('Show subtasks'),
      '#default_value' => isset($this->value) ? $this->value : NULL,
    );
    return $form;
  }

}

When by default in views UI settings it's dissabled it works fine. But when It's enabled by default in views UI id doesn't respect default value and $_GET parameter.

I can't understand this strange behaviour of single on/off checkox in exposed filters in view.

I tried also to use '#attributes' => array('checked'=>'checked') but filter didn't work correct.