I've been synching a multicam timeline for a doc I'm cutting, and upon adding the external audio (2 mic track and a mixdow) and synching it with the camera, I'm updating the multicam track. But then, Avid deletes all but one of the external audio tracks. 

Is there any way to edit multicams to stop them from doing this? I need all the audio because the mics are between two different characters. Any ideas how to fix this? 

https://www.reddit.com/r/editors/comments/xkyb3w/how_to_get_an_avid_group_clip_with_multiple_audio/

If you can post before & after screenshots or detail your workflow, it may help.

the above link  has a good workaround, which may apply in your situation. 

Is the external audio a polyphonic WAV or a mono file? Are you sure it's deleting them and not just placing all 3 tracks on A1? If you flip between your groups on A1 do you see the other tracks as options? (right click the clip in the timeline and you'll see the other cameras or audio in the group clip)

Normally when you add monophonic tracks to Avid it assigns the track number as A1 (you can see this by displaying the "Tracks" column in your bin) If both your mics and your mixdown are all assigned as A1, then when you group, they will all be placed on A1 and you will have to flip through them manually like you would any other group.

If this is the case, you can avoid this by renaming the mono wavs _before_ import so that Avid assigns them different track numbers (A2, A3 etc.). Simply add _2 or _3 to the end of the file name (but before the extension eg. micaudio1_01.wav, micaudio2_02.wav etc) and Avid will use that information to assign the corresponding track. 

So you could have Mic #1 on A1, Mic #2 on A2 and mixdown on A3. Then when you group, these mono elements will be placed on A1,2,and 3 respectively. So now you can checkerboard the audio properly if needed or just thave them all accessible at once on the group clip.

Hopefully that's the issue you#re experiencing, not that Avid is randomly deleting audio tracks. If that's the case then that's a different thing entirely.

Andi

There was a bug on later versions where this had stopped working I think but I am on 2018.12.15 and it works fine.

Here's the thread for that bug, I really hope they fix that as a priority as that's an essential part of my workflow and yet another reason I won't be upgrading any time soon:

Andi