It seems there is a problem in the editor related to toggling the “Closed Loop” property directly on a Spline Component in the Details panel and expecting its value to applicable in the owner actor blueprint. In short the property is always false in the Construct script of a blueprint. This is a problem for updating a spline mesh in edit mode.
It turns out I had initially reported this bug in the wrong section, possibly because of a mouse scroll wheel action when selection the section. Here is the link to the post with the full details:
Hopefully someone at Epic can fix the problem. Thanks for any assistance on this.