Noel's suggestion to use the Audio Editor worked when I tested because I found the audio editor's volume automation can affect midi, supermidi, artist performance tracks, realtracks and realdrums on the original tracks as well as the Utility Tracks and the Master Track will do a Fade Out to a midi Style Song.

In the attached images below, the first screen shot is a SuperMidi organ that was volume automated to mute a region while in its native midi state and afterward converted to an Artist Performance Track in order to display the WAV form in this post.

The second screen shot shows Master Track volume automation. Although no WAV form displays, the automated song Fade Out works.

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Fade a Midi Song in BIAB.jpg (191.07 KB, 31 downloads)

BIAB 2025:RB 2025, Latest builds: Dell Optiplex 7040 Desktop; Windows-10-64 bit, Intel Core i7-6700 3.4GHz CPU and 16 GB Ram Memory.