Generally the audio track will only be imported with the BIAB MGU file, if you have saved an audio track somewhere along the way with that MGU file. Take a look in your BIAB folder where you keep your MGU files and see if you have a wave file of the same name as the MGU file.
Also if you had tried to use an RT in the MGU file and then had saved the MGU, the RT would show up as well.

Cheers - Ian


Ian
My "Original Tunes" Site
My gene pool needs more chlorine.