AJAX in a plugin form results in "The specified #ajax callback is empty or not callable."

I have a configuration form for a Condition plugin I want to have ajax in. When selecting from this field, I want to get a list of displays for that View:

  public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
    $form = parent::buildConfigurationForm($form, $form_state);
    $views = $this->entityTypeManager->getStorage('view')->loadMultiple();
    $options = [];

    /** @var \Drupal\views\Views $view */
    foreach ($views as $view) {
      $options[$view->id()] = $view->label();
    }

    $form['#prefix'] = '<div id="views-settings">';
    $form['#suffix'] = '</div>';

    $view_id = $form_state->getValue('view_id');

    if (empty($view_id)) {
      $view_id = $form_state->getUserInput()["conditions"]["sfp_condition_view_not_empty"]["view_id"] ?? NULL;
    }

    if (empty($view_id)) {
      $view_id = $this->configuration['view_id'] ?? NULL;
    }

    $displays = isset($view_id) ? $this->getViewsDisplays($view_id) : [];

    $form['view_id'] = [
      '#type' => 'select',
      '#title' => $this->t('View'),
      '#required' => TRUE,
      '#options' => $options,
      '#default_value' => $view_id ? $options[$view_id] : '',
      '#ajax' => [
        'wrapper' => 'views-settings',
        'callback' => '::updateViewsDisplay',
        'event' => 'change',
      ],
    ];

    if (!empty($displays)) {
      $form['view_display'] = [
        '#type' => 'select',
        '#title' => $this->t('View display'),
        '#required' => TRUE,
        '#options' => $displays,
        '#default_value' => $displays[$this->configuration['view_display']] ?? $displays['default'],
      ];
    }

    return $form;
  }

      /**
       * Trigger form rebuild.
       *
       * @param array $form
       * @param \Drupal\Core\Form\FormStateInterface $form_state
       * @return array
       */
      public function updateViewsDisplay(array $form, FormStateInterface $form_state) {
        return $form;
      }

Xdebug hits the method fine, but I get this AJAX error:

"The specified #ajax callback is empty or not callable."

and nothing happens after that.

I checked elsewhere where I have done this and the only difference I can see is the ones that worked are regular Drupal Form API forms, and this is a plugin form passed from buildConfigurationForm. Outside of that, I am not seeing the issue.

Thanks to Clives link, for reasons I am not 100% on the configuration forms for a Context plugin the AJAX callback needs to do this:

  /**
   * Trigger form rebuild.
   *
   * @param array $form
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   * @return array
   */
  public function updateViewsDisplay(array $form, FormStateInterface $form_state) {
    $triggering_element = $form_state->getTriggeringElement();
    $parents = array_slice($triggering_element['#array_parents'], 0, -1);
    return NestedArray::getValue($form, $parents);
  }

Then it began to work.

Also, the AJAX declaration needed to be:

'callback' => [$this, 'updateViewsDisplay'],

I assume this has to do with it being a 'form within a form'.