i'm a bit confused.......if you render your BIAB song to audio it makes an audio file - wav or mp3 - so how do you know the drums are midi when you play the audio file? i think there's a bit of confusion about what you are doing - do you mean that when you render a track to audio (by which i presume you mean a wav or mp3 file) the BIAB mixer drum track turns yellow and you are left with your BIAB project, a wav (or mp3) file as well and a midi drum track in BIAB that was RealDrums?

that is very odd