When in the Studio window of Studio Mode, why is the Audio Recording function at times unavailable?

There are two different areas where you can record audio in the Studio window. The Audio Recording function in the Audio track is for video narration only. Thus, it is unavailable if you do not have content in the Video track. If you simply wish to record audio, we recommend that you use the recording function available when you click the Video Capture icon, or else switch to the Capture tab.