Common causes and fixes: specs, audio rights, connectivity, cache, and re-encode flow.
What to do
Identify the failing stage: file upload, validation, processing or publication. Keep the master file, play the actual export and compare it with the composer's media guidance.
Practical example
An editor checks a new export and the recorded publishing result before replacing a stalled upload.
Check your result
Preserve the error and existing identifier. Repeated submissions can create duplicates if the first attempt later completes.