Fullcalendar View Integration: Problem with joins "Field is unknown"

The Fullcalendar View integration works well so long as the the Smart Date field is directly attached to the entity being queried by the view. But if it's attached through a relationship, then attempting to view he calendar yields this error:

 InvalidArgumentException: Field field_when is unknown. in Drupal\Core\Entity\ContentEntityBase->getTranslatedField() (line 587 of core/lib/Drupal/Core/Entity/ContentEntityBase.php).
Drupal\Core\Entity\ContentEntityBase->get('field_when') (Line: 57)
Drupal\smart_date\Plugin\FullcalendarViewProcessor\SmartDateProcessor->process(Array) (Line: 39)
template_preprocess_views_view_fullcalendar(Array, 'views_view_fullcalendar', Array) (Line: 287)
Drupal\Core\Theme\ThemeManager->render('views_view_fullcalendar', Array) (Line: 431)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 444)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 200)
Drupal\Core\Render\Renderer->render(Array) (Line: 450)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1) (Line: 110)
__TwigTemplate_11a731d2877b9468b744d41fcc439cdebfbcb6b469dda518be48813f789db0cf->doDisplay(Array, Array) (Line: 405)
Twig\Template->displayWithErrorHandling(Array, Array) (Line: 378)
Twig\Template->display(Array) (Line: 390)
Twig\Template->render(Array) (Line: 65)
twig_render_template('core/themes/classy/templates/views/views-view.html.twig', Array) (Line: 384)
Drupal\Core\Theme\ThemeManager->render('views_view', Array) (Line: 431)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 444)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 200)
Drupal\Core\Render\Renderer->render(Array, ) (Line: 241)
Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}() (Line: 573)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 242)
Drupal\Core\Render\MainContent\HtmlRenderer->prepare(Array, Object, Object) (Line: 132)
Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse(Array, Object, Object) (Line: 90)
Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray(Object, 'kernel.view', Object)
call_user_func(Array, Object, 'kernel.view', Object) (Line: 142)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch(Object, 'kernel.view') (Line: 163)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 80)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 57)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 91)
Drupal\shield\ShieldMiddleware->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 52)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 706)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)