Avidemux+cannot+use+that+file+as+audio+track

The dialogue box stayed hidden. The track appeared in the slot, ready and waiting. Elias hit "Save," and watched the progress bar sprint toward 100%. As the sun began to bleed through his blinds, the "File saved successfully" notification appeared—the most beautiful sentence he had ever read.

If you don't have a video, you may need to use a different tool like Alternative Tool: FFmpeg (Command Line) avidemux+cannot+use+that+file+as+audio+track

Use File > Open to load your main video file. Do not add the external audio first. The dialogue box stayed hidden