Note: this behavior may be applied to all other relevant manipulation properties

To reproduce:

            this.radDiagram1.IsDraggingEnabled = true;
            RadDiagramShape shape1 = new RadDiagramShape();
            shape1.Text = "Shape1";
            shape1.BackColor = Color.Red;
            shape1.IsDraggingEnabled = false;
            shape1.ElementShape = new RoundRectShape(5);
            this.radDiagram1.Items.Add(shape1);

As a result you will be able to drag the shape which is not correct.

Workaround: set the RadDiagramShape.IsDraggingEnabled  after the shape is added to the diagram:

this.radDiagram1.IsDraggingEnabled = true;
RadDiagramShape shape1 = new RadDiagramShape();
shape1.Text = "Shape1";
shape1.BackColor = Color.Red;         
shape1.ElementShape = new RoundRectShape(5);
this.radDiagram1.Items.Add(shape1);
shape1.IsDraggingEnabled = false;