ffmpeg - video conversion with multiple audio tracks
Use

ffmpeg -i "!original!" -map 0:v -map 0:a -c:v libx265 -preset medium -crf 28 -c:a copy "g:\Prepare\Convert\!file!"


FFmpeg by default only picks one video, audio and subtitle track (if they are present) from among the sources. Express map assignments are required in order to include other streams. 0:a selects all audio streams.