Trusted Signing: Public Trust certificate profile creation fails with 'Some error occured'

I'm trying to create a Public Trust certificate profile under my Trusted Signing (Artifact Signing) account so I can sign Windows executables, but profile creation fails immediately.

Error (Azure CLI --debug, from the ARM operationStatus): error.code = "UnknownError", message "Some error occured. Correlation id - 800b9fec-f884-41f8-b558-f8f3be3fa0ee." Earlier portal attempt: correlation id 52e515a9-63cd-4e36-b052-dce38f666c52.

What I've verified (all clean): identity validation (Individual, US) = Completed; billing account type = Individual, US, matching name/address; Microsoft.CodeSigning provider = Registered; subscription = Pay-As-You-Go/Enabled; the create is accepted (I have permission). Generated certificate subject preview is correct.

The operation runs ~9s then Failed with UnknownError; no further detail in the resource or Activity Log. I've reproduced it 6 times (portal + CLI); newer attempts sit in "Creating" ~30-60s before failing.

Question: What causes this backend "UnknownError" when creating a Public Trust certificate profile right after an INDIVIDUAL US identity validation completes (which the docs say is supported)? Is this a propagation delay (validation completed ~14h ago), or a server-side issuance state that needs Microsoft to clear it via the correlation id? Thanks!