If you’ve rebooted the car via the engineering mode, it has done a full reboot of the MMI. Make sure you have the data connection in your car, you should see the LTE connection. Log out of the MMI by selecting the Guest user. Let this log in fully. Leave this a few minutes. Then log back in with you myAudi user. Again, let this login for a few minutes. Then go to your maps app (Google/Apple whatever you use). I use an iPhone so I find an address click Share and choose the myAudi app. This opens the myAudi app and click Send. In the car select navigation and select received destinations. It can take a few minutes to receive the destination. If it still doesn’t work contact Audi digital services and open a case