I've had something similar happen, twice. The more recent time was about a month ago and sounds closer to your issue.
I got in the car and there was a notification that maps had been updated. Great. I cleared that notification and then noticed the error icon at the top of the touchscreen. Tapping that showed "Navigation unavailable. Navigation maps are not loaded." The icon next it showed MCU_w007, which is an internal fault code.
Note that there are actually 3 separate functions here: The "maps", which confusingly is the turn-by-turn navigation routing function, the map tiles, which you see on the screen, and the function that lets you enter a business name or point of interest and then translates that into a street address.
The first one is the only thing failing in this case. The location text at the bottom of the map also showed the city that I was in when it failed, not the current street and city like usual.
I scheduled mobile service with the app. The night before they were supposed to come out, I was driving and noticed that the location text at the bottom of the map was again showing the current road and correct city, so I cancelled the appointment.
My guess is that someone remotely fixed something, but I didn't get any communication from Tesla to confirm it and wouldn't have even noticed that it was fixed if I hadn't been driving the car the night before the appointment.
By the way, the first time this happened, the mobile technician said the problem was due to connecting to a Wi-Fi network, but not often enough. If there is a map update available, the car doesn't notify you like a firmware update. Instead, it just does it in the background without warning. The first step is to delete the existing map data, then it starts downloading new data (see anything wrong with this logic?) If it doesn't complete its download because you moved it out of Wi-Fi range (since, it's, you know, a car, and pretty mobile) it tries again a few more times and eventually gives up and throws the error. At that point, it can't/won't fix itself the next time you do get into Wi-Fi range; it requires intervention from Tesla. The technician and I had to find a place with strong Wi-Fi where the car could be parked for several hours (hard to do in an apartment setting) then the technician started the download remotely.
