Index: Ringtoets/HeightStructures/src/Ringtoets.HeightStructures.Forms/Views/HeightStructuresFailureMechanismView.cs
===================================================================
diff -u -r06c3ea29cfced4bf3c52d1507b66752797fcfddd -r83ac738ad69ef53eba6ca4f647657e5b7f024b96
--- Ringtoets/HeightStructures/src/Ringtoets.HeightStructures.Forms/Views/HeightStructuresFailureMechanismView.cs	(.../HeightStructuresFailureMechanismView.cs)	(revision 06c3ea29cfced4bf3c52d1507b66752797fcfddd)
+++ Ringtoets/HeightStructures/src/Ringtoets.HeightStructures.Forms/Views/HeightStructuresFailureMechanismView.cs	(.../HeightStructuresFailureMechanismView.cs)	(revision 83ac738ad69ef53eba6ca4f647657e5b7f024b96)
@@ -90,7 +90,8 @@
             structuresObserver = new Observer(UpdateMapData);
 
             calculationInputObserver = new RecursiveObserver<CalculationGroup, HeightStructuresInput>(
-                UpdateMapData, pcg => pcg.Children.Concat<object>(pcg.Children.OfType<StructuresCalculation<HeightStructuresInput>>().Select(pc => pc.InputParameters)));
+                UpdateMapData, pcg => pcg.Children.Concat<object>(pcg.Children.OfType<StructuresCalculation<HeightStructuresInput>>()
+                                                                     .Select(pc => pc.InputParameters)).ToArray());
             calculationGroupObserver = new RecursiveObserver<CalculationGroup, CalculationGroup>(UpdateMapData, pcg => pcg.Children);
             calculationObserver = new RecursiveObserver<CalculationGroup, StructuresCalculation<HeightStructuresInput>>(UpdateMapData, pcg => pcg.Children);
             foreshoreProfileObserver = new RecursiveObserver<ForeshoreProfileCollection, ForeshoreProfile>(UpdateMapData, coll => coll);