diff --git a/awx/api/generics.py b/awx/api/generics.py
index 7b58f14edb..7a818722bc 100644
--- a/awx/api/generics.py
+++ b/awx/api/generics.py
@@ -412,6 +412,8 @@ class SubListCreateAttachDetachAPIView(SubListCreateAPIView):
         # Verify that the relationship to be added is valid.
         attach_errors = self.is_valid_relation(parent, sub)
         if attach_errors is not None:
+            if created:
+                sub.delete()
             return Response(attach_errors, status=status.HTTP_400_BAD_REQUEST)
 
         # Attach the object to the collection.
diff --git a/awx/api/views.py b/awx/api/views.py
index a5a85f2fdf..910eae869b 100644
--- a/awx/api/views.py
+++ b/awx/api/views.py
@@ -2669,8 +2669,10 @@ class WorkflowJobTemplateNodeChildrenBaseList(EnforceParentRelationshipMixin, Su
                 related_nodes = getattr(workflow_node, node_type).all()
                 for related_node in related_nodes:
                     graph.add_edge(workflow_node, related_node, node_type)
-                    if not find and parent == workflow_node and\
-                       sub == related_node and self.relationship == node_type:
+                    if (not find and
+                        parent == workflow_node and
+                        sub == related_node and
+                        self.relationship == node_type):
                         find = True
         if not find:
             graph.add_edge(parent, sub, self.relationship)