I and a small handful of others had problems with the navigation in Android Auto after doing the RRT 18-087 fix for the U73 recall (that fix won't apply to you since you had the U73 recall recently and will already have the fix). I think the technicians do a power down of the 12 volt system before applying these firmware updates and that sometimes messes things up. Or maybe they didn't do the power down that they were supposed to do and that messed things up. You didn't say, but it doesn't sound as if you are talking about Android Auto, but rather the built in navigation system. You also didn't say what model year it is -- the UConnect system in the 2017s are quite a bit different from the 2018s and later. If you are talking about Android Auto these are the things I did to get it working again:
1. In UConnect go to Apps - Settings - Phone/Bluetooth - Smartphone Projection Manager -and make sure the Smartphone Device Mirroring box is checked.
2. In the Android Auto app on the phone tell it to forget all connected vehicles.
3. Clear the Android Auto application data on the phone from within the Android settings screen for Apps.
4. Tell UConnect to clear Personal Data. This of course causes it to lose radio station presets and customization of the UConnect apps screen.
5. Pull and reinsert fuse F76.
After you pull and reinsert the fuse you will notice some weirdness on the Media screen. It will show two USB buttons instead of just one. Also the Apps screen will be missing some icons. This will go away and it will go back to normal if you wait a few minutes and then turn the car off, open and close the door and then restart the car.
2018 Molten Silver Pacifica Hybrid Limited purchased Nov 30, 2017.