Copilot Chat (Microsoft 365) - Sonnet model always returns "Oops! Something happened"!

I'm having an issue with Microsoft 365 Copilot Chat in my organization's tenant and I'm wondering if anyone else has experienced the same problem.

Issue:

• Tenant: Microsoft 365 Copilot (Work)
• Claude Opus model works without any issues.
• Claude Sonnet model consistently fails.
• As soon as I send a prompt using Sonnet, I get the error:

  "Oops! Something happened. Can you try again?"

The problem only occurs with Sonnet. If I switch back to Opus, the exact same prompt works immediately.

Has anyone seen this before or found a solution?