I know the issue of apple carplay not giving audio output for navigation like Waze. This has also occurs when the system tries to read text messages as well. I also noticed this issue with the factory (Garmin) navigation which I never used. Unfortunately the dealership will not do anything since I have aftermarket speakers, dashcam, radar detector, taillights etc. They said if I put the car back to factory then they would cover under warranty but it will be too much work to remove all that wiring from the vehicle. Even though the only wires actually ties into the vehicle are 3 power wires, this is the way the cookie crumbles.
I had this issue before the newest update in April and still have this issue after the update (18AA-2071-001). This update solved the issue for many people except myself. Also, this issue occurred before any modifications were done to the vehicle and I would find it hard to believe that any of my modifications could cause this issue. The center speaker that plays the inaudible notifications still plays all the dings/dongs, the object sensing, etc., so I know the speaker isn't the issue.
The stealership's best guess is something might be fried in the unit that controls these signals. I know there is an audio unit (grey metal box) and the actual touch screen. Does anyone have knowledge of where these missing signals come from? I am guessing the screen doesn't process any of these signals. I can also still here the "button" clicks when navigating through the touch screen. Would that mean that if it was an actual hardware issue, it would be the audio unit? This is of course is assuming there are no actual wiring issues and it is still not a software issue.