diff --git a/Model/ModelRegistry.php b/Model/ModelRegistry.php
index 53a9641..7cc20f8 100644
--- a/Model/ModelRegistry.php
+++ b/Model/ModelRegistry.php
@@ -98,13 +98,14 @@ final class ModelRegistry
 
                 $this->api->getDefinitions()->set($name, $schema);
             }
+        }
 
-            if (0 === count($this->unregistered)) {
-                foreach ($this->alternativeNames as $model) {
-                    $this->register($model);
-                }
-                $this->alternativeNames = [];
+        if (empty($this->unregistered) && !empty($this->alternativeNames)) {
+            foreach ($this->alternativeNames as $model) {
+                $this->register($model);
             }
+            $this->alternativeNames = [];
+            $this->registerDefinitions();
         }
     }
 
diff --git a/ModelDescriber/ObjectModelDescriber.php b/ModelDescriber/ObjectModelDescriber.php
index 56a1fdb..a7f9634 100644
--- a/ModelDescriber/ObjectModelDescriber.php
+++ b/ModelDescriber/ObjectModelDescriber.php
@@ -45,7 +45,7 @@ class ObjectModelDescriber implements ModelDescriberInterface, ModelRegistryAwar
         $class = $model->getType()->getClassName();
         $context = [];
         if (null !== $model->getGroups()) {
-            $context = ['serializer_groups' => $model->getGroups()];
+            $context = ['serializer_groups' => array_filter($model->getGroups(), 'is_string')];
         }
 
         $annotationsReader = new AnnotationsReader($this->doctrineReader, $this->modelRegistry);
diff --git a/Tests/Functional/TestKernel.php b/Tests/Functional/TestKernel.php
index ff0207d..958b5e6 100644
--- a/Tests/Functional/TestKernel.php
+++ b/Tests/Functional/TestKernel.php
@@ -104,6 +104,10 @@ class TestKernel extends Kernel
             'serializer' => ['enable_annotations' => true],
         ]);
 
+        $c->loadFromExtension('twig', [
+            'strict_variables' => '%kernel.debug%',
+        ]);
+
         $c->loadFromExtension('fos_rest', [
             'format_listener' => [
                 'rules' => [