AI Studio voice replication returns HTTP 404 — “Requested entity was not found”

Google AI Studio
1

Voice replication in Google AI Studio fails after recording the voice sample and consent statement and clicking Replicate voice.

Model: gemini-3.8-flash-tts

The failed MakerSuiteService/CreateVoice request returns HTTP 404 with this complete response:

[5,"Requested entity was not found."]

I verified that:

  • The project is on paid Tier 1 with prepaid credit available.
  • Gemini API is enabled.
  • The API key is available and restricted to Gemini API.
  • My account has the project Owner role.

The error persists with a newly created project and API key.

Does Gemini 3.8 voice replication in AI Studio require additional approval or allowlisting? If not, is this a known issue, and how can I identify which resource wasn’t found?