Approximately 5 hours later, just as I was about to arrive, the car finally managed to figure out my correct location.
Exciting trip, not a huge fan of Teslas, but their charger planning is really nice. It was very unpleasant to suddenly lose it.
I just genuinely wonder how such a bug can actually occur, surely you'd update the GPS fix more often than every couple of hours. Hard to imagine the car just suddenly couldn't get a GPS fix for hours either. But if it did somehow totally lose the ability to use GPS, the car must have a pretty good dead reckoning system given how well it was responding to my changes in direction.
On a vaguely related note, driving 3000 kilometers through Europe in an electric car was surprisingly nice. Certainly didn't affect the length of the trip nearly as much as I'd have expected, but it was certainly super annoying to try and figure out the optimal rate of travel on the Autobahn. Charging at Tesla's supercharges was vastly more expensive than I expected, the "fuel" costs weren't much lower than what you could easily reach with a diesel car.