I was a bit puzzled when I exported my animation to a MP4 to upload to YouTube only to discover that the audio didn’t play. On checking the documentation, I found that this was ‘normal’. I had to use Final Cut Pro to combine my animation and audio. It worked-out okay in the end, but this should really be possible without resorting to using another program. Not only that, but I would like some minimal audio editing on the timeline - trimming and adding fades in and out.
Thanks for the request; we understand how painful this is.