I had to change planned course (mostly due road works) a few times, but even after a few km, Edge still navigated me to do U-turn and go back. I think its, because it cannot recalculate to next course point and when I joined planned course a few km further it did not advice me to continue the course but sent me back to previous point. When It was rarely able to recalculate a course in the past, Edge used still elevation graph for original course and therefore there was not dot for my position displayed - it is definitely bug.
I have had a few times problem with V-shape junctions - there was no turn prompt. So I have to stop, go from data screen to map screen in order to know where to go.