What happened
Voices not assigned. For example: Some speakers of project 6f1c2b7e have no voice.What to do
Assign voices with updateSpeakerVoice, or wait for voice matching to finish.wait: work in progress blocks the request; wait for it to end, then retry.
same_key: resend the same request with the same Idempotency-Key (after Retry-After when given).