ID 422586 - [S] To Avid: Publish failure when expected DNxHD doesn't exist

Problem summary
When publishing to Avid, during the creation of the AAF for all panels, the publish sometimes fails with the error "no media objects for ref 'dnxhd'".
This can occur when a publish for this Sequence had been previously attempted, but failed.

Customer reported version
Flix 6.2.1

Customer reported platform
CentOS 7

Steps to reproduce

Note: this is an intermittent issue and following these steps will not reproduce it 100% of the times.

1) Publish a Sequence Revision to Avid. After having created the *_new.aaf, Flix fails to create the *_all.aaf due to missing DNxHDs.

Expected behaviour
If no DNxHD is found, Flix should re-create it.
If this is not possible, the Server should at least release the *_new.aaf to the Client.

Actual behaviour
Flix states that due to a Server error it was not able to successfully publish. Checking the Server logs will show that the *_new.aaf was actually created, and only the *_all.aaf failed.

Workaround
1. Select all panels
2. Version them up
3. Save a new Sequence Revision
4. Publish to Avid

Reproduced by support
6.2.2 - CentOS 7 Server
6.2.1 - CentOS 7 Server