thanks you.
i check my saved routes using Basecamp and the points in the route are indeed shaping points.
this will explain while on my test routes i don't actually have to get to the point that is at the apex of a u-turn, it jumps to the next point.
i assume i had got close enough to the waypoint for it to register.
now i know it saw the other pint closer to me than the apex point.
thank you