Your Garmin help, please

Have you actually tried to use it to get you to the start, even though it is showing a straight line it may actually route you along the roads. If it doesn't try as below.

Make a new route from your current position to the start of the course.
"Where to" select concentric circle icon at the bottom of screen, this will give you the option to select a point on the map, select the start of your course, it will calculate a route for you.

Thanks. I'm going to look into this and will report back...