Download export file checkbox is hidden when it should not be

Download export file checkbox appears to be hidden even when you select Delimited text and have less than 500 (or other default number) submissions. This happens when PDF documents were selected by default.

Steps to reproduce:

1. Enabled Webform Entity Print (PDF) module
2. Create a webform
3. Submit form 11 or more times
4. Gt to the Results -> Download page
5. Select PDF documents as an export format
6. Hit save settings
7. Now select Delimited text as an export format
8. See that Download export file checkbox is not appearing at the download options fieldset

Here is a logic which makes this checkbox to be hidden:

    $form['export']['download']['download'] = [
      '#type' => 'checkbox',
      '#title' => $this->t('Download export file'),
      '#description' => $this->t('If checked, the export file will be automatically download to your local machine. If unchecked, the export file will be displayed as plain text within your browser.'),
      '#return_value' => TRUE,
      '#default_value' => $export_options['download'],
      '#access' => !$this->requiresBatch(),
      '#states' => $states_archive,
    ];

Checkbox does not appear because Download fieldset is generated once, but not per exporter. Also it is not getting rebuild in AJAX in case if Exporter format is changed.

The easiest solution would be to rebuild Download fieldset in AJAX on Exporter format change.

Also I noticed it does not work in other way, e.g. if you select Delimited text exported as a default and save it, and than select PDF exporter you can see that Download file checkbox getting hidden.