Same issue here, the problem only exists on iPhone 14. We sent a very small app to Apple showing the issue, and the only response we got was 'works as designed'. Clearly not the case. We set our callback size to 1024 samples, and with RemoteIO we get exactly 1024 each time. However, with VoiceProcessingIO we get mostly 960 with the occasional 1440 callback, and it is at the 960/1440 callback boundary where the render errors occur, resulting in loss of microphone data.