All scheduled prompts failing — "couldn't be completed" error — Power Platform provisioning issue?

I'm hoping someone from Microsoft or the community has seen this. All my scheduled prompts are failing at execution time with this error:

"This scheduled prompt couldn't be completed. It will be retried during the next scheduled run."

Key facts:

• M365 Copilot license on a direct Business subscription
• The same prompts run correctly in Copilot Chat
• Even the simplest scheduled prompt fails: "List emails I received in the past 5 days. No analysis needed — just the list."
• The scheduling UI works fine — prompts appear in the Active list with correct schedules
• Failure is at execution time. Retries also fail.

Admin-side investigation already completed:

• Power Platform environment: Ready
• No DLP policies in the tenant
• No admin toggle for scheduled prompts exists in M365 admin center (noted as unusual)
• Org-level optional connected experiences: enabled
• User-level optional connected experiences toggle absent (consistent with org locking it On)

The absence of an admin toggle for scheduled prompts in the M365 admin center is the one thing that stood out — I wonder if this indicates the feature wasn't fully provisioned when the Copilot license was applied.

Sharing here in case this is a known issue or others are experiencing the same. Any insight from Microsoft engineers or others who've resolved this would be appreciated.