Steps to reproduce:
1. Upload mp4 without video track but with audio track
Publish engage fails with unmet criteria.
Workflow sucessfully completes.
I tested with todays r/2.0.x with the minimal workflow in the old admin ui. My mp4 has no video track but one AAC audio track.
The reason for this failing is that the new admin-ui does not distinguish between multi-file-upload and single file upload.
The "audio-only" upload field really is only meant for "an additional audio stream to mux into the video".
If uploaded as presentation/source, the workflow fails as well.
If uploaded as presenter/source, the workflow runs through.
I think I have found the issue and solved it in this pull request:
The problem was that the audio only track was given the flavor presenter-audio/source even if the presenter/source track was not present. I have fixed it by assigning the audio track the presenter/source flavor if there are no other present tracks.
I don't think we should change the flavor of an audio track. The issue is as far I can see only a workflow issue.
Sorry I mixed up something here, your pull request 521 looks good to me.