Hi Peter,
I started having this problem in June. My audio completely drops out. Screen works and it shows a signal, no radio, Sirius, or phone(callers can hear me but I can't hear them). I think this is different than the Sirius antenna issue. In June they replaced my amplifier, then they replaced the APIM module. Audio worked for 3 weeks then went off intermittently, finally went out all together. It went back today for the third time for the same problem. At this point I am not very confident they will be able to resolve it. I am really bummed because I love this car.
2015 MKC 2.3
Tuxedo Black
Reserve package
Purchased August 2014