2
Are you sure your playback software (player, game engine) doesn't have a fadeout? That is a really short sound, so you might want to look into settings.
Also, have you tried to open the reversed file in audition after export? Is it cut off or full?
So:
if its full -> check your playback settings
if its short -> use any other free software like ...
Only top voted, non community-wiki answers of a minimum length are eligible