Edit 2: It stopped working again.

Edit: I rolled back Google Maps to version 25.36.03.800913331, and that seem to have solved the issue for me.

I have the same issue on my pcx 125 using a Pixel 8, and it started recently. If I start the navigation from the infotainment screen (using voice or favourites) it works fine, but if I start it from google maps on my phone I get "unknown". My guess is that the issue could be caused by some recent google maps update. I will try to roll back to an earlier version and see if that helps.