Actually Correct..even I am facing the same issue-if there is on tab, then tabs section don't appear at all.
Can this pkce patch be released in next alpha release?
After applying MR 29 , on page load I got another issue
Fatal error: Could not check compatibility between Drupal\markdown\Form\SubformState::createForSubform(array &$subform, array &$parent_form, Drupal\Core\Form\FormStateInterface $parent_form_state, ?Drupal\markdown\Form\FormInterface $subform_form_object = null) and Drupal\Core\Form\SubformState::createForSubform(array &$subform, array &$parent_form, Drupal\Core\Form\FormStateInterface $parent_form_state, ?Drupal\Core\Form\FormInterface $subform_form_object = null), because class Drupal\markdown\Form\FormInterface is not available in \web\modules\contrib\markdown\src\Form\SubformState.php on line 57