@Jack B please find the sldprt file

Hi, here you are, when are you trying setting the line for a boundary surface, or any surface connected with a few lines, the lines must be set as solid connected. During the selection, you can see any single point as a point if the single lines are connected, or as a circle if not. Photo UAV„01B”.jpg That is the first information. The second information you will have when you are trying any way to use those lines is that the lines aren't continuous. Photo UAV„01C”.jpg

Hi anome anome, you have two problems, first one - is the sketch named „Sketch6” is without a continuous - photo UAV„01”.jpg
For the second issue, I split the curved surface into five surfaces - photos UAV„03”.jpg - UAV„07”.jpg
As a result, you can see the photo UAV„02”.jpg and open the attached IGS file.