Error 715-123420 on every model deployment (Anthropic and Azure OpenAI), new pay-as-you-go subscription, support cases bounced twice

Since 22 September 2026 every model deployment on a new pay-as-you-go subscription fails with error 715-123420 ("Our system has detected this request as unusual activity for your account. If you are confident this is in error, please contact support").

What we have checked

• Fails for Anthropic claude-opus-5 and claude-sonnet-5 (Foundry, GlobalStandard, East US 2 and West US 3) and for Azure OpenAI gpt-5.4-mini (GlobalStandard), so it is not model- or Marketplace-specific.
• Fails from the portal and from the CLI (az cognitiveservices account deployment create), and for two different users (an Owner and a Contributor), so the block is at subscription level.
• Quota is available and the Anthropic terms are accepted.
• We have not deleted or recreated the Foundry resource.

Identifiers

• Subscription ID: 5fc71ede-9374-428b-babe-473b9cf5706b
• Foundry resource ID: /subscriptions/5fc71ede-9374-428b-babe-473b9cf5706b/resourceGroups/rg-shane-3419/providers/Microsoft.CognitiveServices/accounts/shane-6742-resource (West US 3)

Support requests so far

• 2609220030001011: closed 29 Sep as a technical misroute, told to buy a Technical support plan.
• 2609290030005588: Billing & Subscription Management replied 6 Oct that it is outside their scope and referred me to this forum.

The subscription has no paid support plan.

The owner is JC Logistics Limited (trading as Veridion Group), a New Zealand company, using the subscription for an internal logistics application.

Could a moderator please route this to the backend fraud protection team for review, as was done in question 5947131? Happy to provide any verification by private message.