I’m on 2018.4.9 though this did happen on previous software as well. From time to time while I use navigation I notice that the turn by turn directions recycle and I end up at a previous spot in the directions d (i.e. 15 miles ago) and the directions, distance remaining, time remaining, and estimated arrival are all based on this bad position. Then, out of nowhere the navigation thinks the car is going 200 MPH and catches back up. Bizarre! Meanwhile my position on the map is always right.