i included two sample files.
"sample 1.mkv" - first stream 6 channels and second stream 8 channels, and everything works fine when "enhancements" are enabled including 8 channel stream.
"sample 2.mkv" - first stream 8 channels and second stream 6 channels, and audio fails when "enhancements" are enabled.
https://www.upload.ee/files/16079189/sample_1.mkv.html
https://www.upload.ee/files/16079191/sample_2.mkv.html