mkvextract doesn't write program config element for AAC audio tracks that need it
mkvtoolnix 20.0.0
resulting file is broken: ffmpeg is unable to use it , stating "avformat_find_stream_info() failed". The only thing that it able to use it at all is VLC (2.2 and 4.0.0) - with some minor problems.
No problems when extracting with the ffmpeg 3.4.1 (haven't tried other versions) and the resulting aac file is 9 bytes larger.
ffmpeg identifies track as "Audio: aac (LC), 48000 Hz, 7.1, fltp (default)"
Here are the differences from the start of the file -
mkvtoolnix:
FFF14C00069FFC
ffmpeg:
FFF14C0007BFFCA09901200021190000
Edited by Moritz Bunkus