The control points are being added to the geometry. The symbol in the case provided is not updating because the dash pattern is using an at-line-end option of 'No constraint,' which does not adjust the dash placement based on the control points. To see the dash pattern adjusted, use an ending option other than 'No constraint.' The control points can also be seen in the editing sketch when modifying the feature if the symbology for control points is enabled in the project options in the Editing section.