@GT-JWR, by "taking 22mi to redraw the route" I understood that there was no recalculation, but it seems that there was, just not in your prefered (or logical) direction then).
It is not that there are parameters to send you "back to the route" against any other logic than the fastest or shortest route. It would have to be simulated to see on what logic the route is been decided. I have no means of assisting in that.