Maybe this problem is related to the iOS System.
In iOS perspective, as far as I know, officially it is not possible. When you start the recording sessions, except for recording does not occupy it. Once you playback and recording sessions in the session must be solved. recording and playback session, the session can not be occupied simultaneously.
refer a apple documentation: Audio Session
AVAudioSessionCategoryPlayAndRecord or the equivalent kAudioSessionCategory_PlayAndRecord—Use this category for an application that inputs and outputs audio. The input and output need not occur simultaneously, but can if needed. This is the category to use for audio chat applications.
In AIR, if you code no problem. most likely this reason.