FFmpeg not copying all audio streams

I’m having trouble getting ffmpeg to copy all audio streams from a .mp4 file. After hours of searching online, it appears this should copy all streams (as shown in example 4 here):

ffmpeg -i in.mp4 -map 0 -c copy out.mp4

in.mp4 contains 3 streams:

• Video
• Audio track 1
• Audio track 2

out.mp4 (which should be identical to in.mp4) contains only 2 streams:

• Video
• Audio track 1

FFmpeg does appear to correctly identify all 3 streams, but doesn’t copy all of them over. Output from FFmpeg:

Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
  Stream #0:2 -> #0:2 (copy)

Edit: Output from ffmpeg -v 9 -loglevel 99 -i in.mp4:

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from in.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf57.36.100
  Duration: 00:00:06.03, start: 0.000000, bitrate: 5582 kb/s
    Stream #0:0(und), 1, 1/15360: Video: h264 (Main), 1 reference frame (avc1 /
0x31637661), yuv420p(tv, bt470bg/unknown/unknown, left), 1920x1080 (0x0) [SAR 1:
1 DAR 16:9], 0/1, 5317 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und), 1, 1/48000: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz,
 stereo, fltp, 128 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
    Stream #0:2(und), 1, 1/48000: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz,
 stereo, fltp, 128 kb/s
    Metadata:
      handler_name    : SoundHandler
Successfully opened the file.
At least one output file must be specified
[AVIOContext @ 0000000001c2b9e0] Statistics: 153350 bytes read, 2 seeks

Edit 2 (solved): I managed to find the correct syntax from this ticket. For any others that are interested, the correct syntax is:

ffmpeg -i in.mp4 -vcodec copy -c:a copy -map 0 out.mp4

This will copy all streams.

Answer

Apparently this is a popular question, so I’m posting my solution as an answer (was previously a comment reply) so that others can see.

I managed to find the correct syntax from this ticket. The correct syntax is:

ffmpeg -i in.mp4 -vcodec copy -c:a copy -map 0:0 -map 0:1 -map 0:2 out.mp4

This will copy all 3 streams.