If I try to export just the audio part of any video and in any format, I get a message that demultiplexer could not be found.
@eumagga0x2a
thanks
To re-import exported audio track in Avidemux, you need to take the path via Audio --> Select Track to point to the file with raw audio exported earlier. The path via File --> Open is for video files only (which may or may not include audio tracks), encapsulated by supported container formats.