I have followed along and even downloaded the Blue Print Splines Track and then tried to refresh the points back to the structure defaults but it doesn’t restore back to the defaults. As the image below shows the track width default is 1 yet it resets to 0 clicking the yellow arrow.
I was able to reproduce this issue on our end. I have submitted a report (UE-7277) to the development team for further consideration. I will provide updates with any pertinent information as it becomes available. Thank you for your information and time.