If you slightly move the construction line within the domain, you will get a continuous line chart. Go to Line geometry and change the Construction method to "Coordinates" and slightly increase the Y coordinate value. For instance, change the Y coordinate value of point 1 from 4.6195m to 4.6196m and the Y coordinate value of point 2 from 3.2249m to 3.225m. See below image showing these changed values and the corresponding line chart plotted for this updated line position. Note that the solution was partially solved only to display the line chart.