AVAudioSession API for setting stereo orientation on supported devices (iPhone XS and above) is completely broken on iOS 15 betas. Even the 'Stereo Audio Capture' sample code does not work anymore on iOS 15. Even AVCaptureAudioDataOutput fails when setting stereo orientation on AVAudioSession. I am wondering if Apple Engineers are aware of this issue and whether this would be fixed in upcoming betas and most importantly, iOS 15 mainline.

Is it necessary for AVVideoCompositionInstruction (custom) to have atleast one video asset track? If one needs to just generate video out of motion graphics and pictures, does one still need to add dummy video track added to composition first?

On an iPhone 12 mini running iOS 15 beta 3, the microphone samples with builtin microphone are all silent in RemoteIO unit callbacks. This happens when AVAudioSession preferredInputSource is set to back or front mic. It is NOT seen when preferred input source is set to bottom mic or with external microphones. Is this a known bug on iOS 15?