Revit is an extensive piece of software. It will take time to get to know it. You have to get the feeling for the basics/concepts than it will become much easier.
What you describe is correct. When you draw line and complete the line it will flash the locks. This happens because Revit automatically continues with the next line (chaining). This is because by default the chain selection box is ticked.

You will see a difference when drawing for example a square (no chaining). In this case after the square is drawn the lock will remain visible because the square is completed and Revit will not continue with the nxt command. So yes the behaviour is as expected.
Normal procedure is to use the align tool. Use align tool, select reference line/plane and then the line. Then the lock will show up.
Often it will also work to draw the line away from the reference plane and then back to it again. After hitting the reference plane the lock will show up again.
Louis

Please mention Revit version, especially when uploading Revit files.