diff --git a/src/applications/project/editor/PhabricatorProjectTransactionEditor.php b/src/applications/project/editor/PhabricatorProjectTransactionEditor.php
--- a/src/applications/project/editor/PhabricatorProjectTransactionEditor.php
+++ b/src/applications/project/editor/PhabricatorProjectTransactionEditor.php
@@ -631,6 +631,7 @@
           }
           break;
         case PhabricatorProjectTransaction::TYPE_PARENT:
+        case PhabricatorProjectTransaction::TYPE_MILESTONE:
           $materialize = true;
           $new_parent = $object->getParentProject();
           break;
@@ -669,6 +670,11 @@
         ->rematerialize($object);
     }
 
+    if ($new_parent) {
+      id(new PhabricatorProjectsMembershipIndexEngineExtension())
+        ->rematerialize($new_parent);
+    }
+
     return parent::applyFinalEffects($object, $xactions);
   }
 
diff --git a/src/applications/project/engine/PhabricatorBoardLayoutEngine.php b/src/applications/project/engine/PhabricatorBoardLayoutEngine.php
--- a/src/applications/project/engine/PhabricatorBoardLayoutEngine.php
+++ b/src/applications/project/engine/PhabricatorBoardLayoutEngine.php
@@ -435,7 +435,7 @@
 
     // If we have proxies, we need to force cards into the correct proxy
     // columns.
-    if ($proxy_map) {
+    if ($proxy_map && $object_phids) {
       $edge_query = id(new PhabricatorEdgeQuery())
         ->withSourcePHIDs($object_phids)
         ->withEdgeTypes(