I think (based on one of your earlier replies), that the way the map is even being presented on your display indicates there is a problem with your system. A problem with the satellite receiver would not result in a system not displaying map data properly (text in white blocks). Even in a highly congested urban location, surrounded by hi-rise towers, you should be able to get enough signal to accurately triangulate your position adequately for navigation purposes. And when you are going through a long tunnel, most systems will attempt to roughly gauge your location based on your travel speed and direction (when actual satellite signal is completely blocked). What you are seeing is a multitude of issues that to me, seem very much related to your infotainment system itself being faulty. IMHO, I think a complete replacement is what should be done by your dealer to rectify this. You know, from using your previous vehicle, how a properly functioning navigation system should operate.It is. No change after updating.
I hope you are able to obtain a replacement system through your dealer and can get back to pleasant and accurate navigation again.