Index: Ringtoets/ClosingStructures/src/Ringtoets.ClosingStructures.Forms/Views/ClosingStructuresFailureMechanismView.cs
===================================================================
diff -u -r4f87cc4af28d688129fd0fb70feabf04dd7b0e59 -r83ac738ad69ef53eba6ca4f647657e5b7f024b96
--- Ringtoets/ClosingStructures/src/Ringtoets.ClosingStructures.Forms/Views/ClosingStructuresFailureMechanismView.cs	(.../ClosingStructuresFailureMechanismView.cs)	(revision 4f87cc4af28d688129fd0fb70feabf04dd7b0e59)
+++ Ringtoets/ClosingStructures/src/Ringtoets.ClosingStructures.Forms/Views/ClosingStructuresFailureMechanismView.cs	(.../ClosingStructuresFailureMechanismView.cs)	(revision 83ac738ad69ef53eba6ca4f647657e5b7f024b96)
@@ -90,7 +90,9 @@
             structuresObserver = new Observer(UpdateMapData);
 
             calculationInputObserver = new RecursiveObserver<CalculationGroup, ClosingStructuresInput>(
-                UpdateMapData, pcg => pcg.Children.Concat<object>(pcg.Children.OfType<StructuresCalculation<ClosingStructuresInput>>().Select(pc => pc.InputParameters)));
+                UpdateMapData, pcg => pcg.Children.Concat<object>(pcg.Children.OfType<StructuresCalculation<ClosingStructuresInput>>()
+                                                                     .Select(pc => pc.InputParameters)
+                                                                     .ToArray()).ToArray());
             calculationGroupObserver = new RecursiveObserver<CalculationGroup, CalculationGroup>(UpdateMapData, pcg => pcg.Children);
             calculationObserver = new RecursiveObserver<CalculationGroup, StructuresCalculation<ClosingStructuresInput>>(UpdateMapData, pcg => pcg.Children);
             foreshoreProfileObserver = new RecursiveObserver<ForeshoreProfileCollection, ForeshoreProfile>(UpdateMapData, coll => coll);