Index: src/Deltares.DSoilModel.Forms/DSoilModelPlugin.cs
===================================================================
diff -u -r141 -r157
--- src/Deltares.DSoilModel.Forms/DSoilModelPlugin.cs	(.../DSoilModelPlugin.cs)	(revision 141)
+++ src/Deltares.DSoilModel.Forms/DSoilModelPlugin.cs	(.../DSoilModelPlugin.cs)	(revision 157)
@@ -481,6 +481,11 @@
                     }
                     UpdatePropertyControl();
                 }
+                if (UndoRedoManager.UseManager == false)
+                {
+                    // note: as the UndoRedoManager is not sending EndAction events the validator can respond to, start it here (see DSB-473)
+                    RealTimeBackgroundValidator.Instance.Start();
+                }
             }
 
             var gridViewControl = sender as GridViewControl;