Index: /trunk/src/VBox/Additions/WINNT/Graphics/Video/mp/wddm/VBoxMPWddm.cpp
===================================================================
--- /trunk/src/VBox/Additions/WINNT/Graphics/Video/mp/wddm/VBoxMPWddm.cpp	(revision 50677)
+++ /trunk/src/VBox/Additions/WINNT/Graphics/Video/mp/wddm/VBoxMPWddm.cpp	(revision 50678)
@@ -3227,5 +3227,5 @@
                 }
 
-                Assert(pSource->u8SyncState == VBOXWDDM_HGSYNC_F_SYNCED_ALL);
+                Assert(pSource->u8SyncState == VBOXWDDM_HGSYNC_F_SYNCED_ALL || pDevExt->aTargets[pDstAlloc->AllocData.SurfDesc.VidPnSourceId].fStateSyncPening);
             }