Can you report it through Feedback Assistant?

AudioDriverKit currently does not support virtual audio devices and entitlements will not be granted for those types of audio drivers. You will need to use AudioServerPlugIn if you want to implement a virtual audio device, which does require a reboot, or at least needs to restart the coreaudiod process.

AudioServerPlugIn is not supported on iOS and is not supported in the App Store. You will need to have your app/driver use an installer, and that is the only option if you want to create virtual audio drivers.

Can you file a request using Feedback Assistant? And please post the FB number in this thread?

The IO buffer frame size that is called on the driver will be determined by the client process and what they configure their audio IO buffer size to use. A driver really shouldn't be in control of this and should be able to handle buffer sizes up to 4096 samples.

AudioDriverKit does not support that currently. You could create a custom user client connection to a daemon or agent to save/restore settings to their DEXT.

Please file a Feedback for this and post the FB number in the thread. Might be useful to grab a sysdiagnose and also capture a ktrace when this issue occurs.