It takes about to 30sec - 1min for nav to find a current location. I had the same problem parking downtown in my office. Once you enter underground parking your last position is remembered but your car is still moving. When you exit your parking, navigation will think that last position=new position (after car is started) and it will continue from there or reset itself.
Unfortunately we can't do nothing about it because it is the way the nav is working.
Unfortunately we can't do nothing about it because it is the way the nav is working.