iPhone 11, Bluetooth connection to two different cars (2009 and 2017 BMWs). If "Hey Siri" is enabled, Siri's responses are not audible (although they are visible in the phone's display). If "Hey Siri" is disabled, and Siri is launched by pressing the side button, it all works fine, with Siri audible as expected through the car's sound system. Very strange. Is this an iOS 13 or iPhone 11 bug?