Index: src/Deltares.DSoilModel.Forms/DSoilModelGeometryEditor.cs
===================================================================
diff -u -r354 -r375
--- src/Deltares.DSoilModel.Forms/DSoilModelGeometryEditor.cs	(.../DSoilModelGeometryEditor.cs)	(revision 354)
+++ src/Deltares.DSoilModel.Forms/DSoilModelGeometryEditor.cs	(.../DSoilModelGeometryEditor.cs)	(revision 375)
@@ -456,8 +456,13 @@
         {
             if (sender == RealTimeBackgroundValidator.ValidationResults)
             {
+                var shapesToRemove = new List<IShape>();
                 foreach (var shape in spatialEditor.Shapes.Where(x => x is DrawingSpecificMechanismPointLocation).ToList())
                 {
+                    shapesToRemove.Add(shape);                    
+                }
+                foreach (var shape in shapesToRemove)
+                {
                     spatialEditor.Remove(shape);
                     spatialEditor.AddShape(shape);
                 }