Panels 4.4 / CTools 3.0 / CachedValuesGetterTrait Error

Hi I have meet this issue as well.
I have tested the same version as you mentioned above in drupal 8.6.10 and drupal 8.6.15
it give me the same error below when clicking Add block button in page manager settings.

Error: Call to a member function getVariant() on null in Drupal\panels\Controller\Panels->getCachedValues() (line 39 of C:\wamp64\www\projects\drupal-861\modules\contrib\panels\src\CachedValuesGetterTrait.php) #0 C:\wamp64\www\projects\drupal-861\modules\contrib\panels\src\Controller\Panels.php(108): Drupal\panels\Controller\Panels->getCachedValues(Object(Drupal\Core\TempStore\SharedTempStoreFactory), 'page_manager.pa...', Array) #1 [internal function]: Drupal\panels\Controller\Panels->selectBlock(Object(Symfony\Component\HttpFoundation\Request), 'node_view--node...', 'page_manager.pa...') #2 C:\wamp64\www\projects\drupal-861\core\lib\Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber.php(123): call_user_func_array(Array, Array) #3 C:\wamp64\www\projects\drupal-861\core\lib\Drupal\Core\Render\Renderer.php(582): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() #4 C:\wamp64\www\projects\drupal-861\core\lib\Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber.php(124): Drupal\Core\Render\Renderer->executeInRenderContext(Object(Drupal\Core\Render\RenderContext), Object(Closure)) #5 C:\wamp64\www\projects\drupal-861\core\lib\Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber.php(97): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) #6 C:\wamp64\www\projects\drupal-861\vendor\symfony\http-kernel\HttpKernel.php(151): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() #7 C:\wamp64\www\projects\drupal-861\vendor\symfony\http-kernel\HttpKernel.php(68): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1) #8 C:\wamp64\www\projects\drupal-861\core\lib\Drupal\Core\StackMiddleware\Session.php(57): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #9 C:\wamp64\www\projects\drupal-861\core\lib\Drupal\Core\StackMiddleware\KernelPreHandle.php(47): Drupal\Core\StackMiddleware\Session->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #10 C:\wamp64\www\projects\drupal-861\core\modules\page_cache\src\StackMiddleware\PageCache.php(99): Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #11 C:\wamp64\www\projects\drupal-861\core\modules\page_cache\src\StackMiddleware\PageCache.php(78): Drupal\page_cache\StackMiddleware\PageCache->pass(Object(Symfony\Component\HttpFoundation\Request), 1, true) #12 C:\wamp64\www\projects\drupal-861\core\lib\Drupal\Core\StackMiddleware\ReverseProxyMiddleware.php(47): Drupal\page_cache\StackMiddleware\PageCache->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #13 C:\wamp64\www\projects\drupal-861\core\lib\Drupal\Core\StackMiddleware\NegotiationMiddleware.php(52): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #14 C:\wamp64\www\projects\drupal-861\vendor\stack\builder\src\Stack\StackedHttpKernel.php(23): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #15 C:\wamp64\www\projects\drupal-861\core\lib\Drupal\Core\DrupalKernel.php(693): Stack\StackedHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #16 C:\wamp64\www\projects\drupal-861\index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request)) #17 {main}.