Hello, I have found a problem in SOLIDWORKS 2019 in the 3D Sketch environment. When I am drawing a line (click to the Draw line button) and use the middle mouse button to rotate an assembly and release the middle mouse button then the line drawing is finished and the line ends in the “random” place where was the mouse cursor when I released the middle mouse button. This is very unhappy and it is different from the previous SOLIDWORKS I had. Do you have the same experience?
I'm not understanding your input sequence. Using a combination of add-on and included tools, I don't have this issue. I rotate primarily with 3D mouse, and initiate a line command with one of: L key shortcut, S menu, or mouse gesture. I haven't clicked the Line button on ribbon since very early days of learning SWx.
What version of SWx (year, SP), input hardware, and initiate command method are you using? Try something different.