This problem has happened to me several times. My Kodiaq is 2018 with the Amundsen navigation unit and the CANTON sound system. I’m not sure if a smar****ch (in my case the Apple Watch 4) plays a role in that. I use Apple Carplay with a wireless adapter (but a similar problem has happened before without a wireless adapter). This usually happens after I receive a call via whatsapp or facebook messenger. After the call is completed, the system remains muted, instead of returning to the song (or radio station) that was played before the call. Whatever I tried, there is no sound, not even switching to another radio station or other source in Amundsen, disconnecting carplay, etc. Restarting the iPhone or Amundsen didn’t help as already explained here (because it returns to the same state). The only thing that helps is turn off the car, lock it, wait a while (today that was enough for 1 min) and start it again.