Copilot Excel error "Failed to fetch document context" - Cannot use paid service

Environment:

• Microsoft 365 (paid subscription, recently upgraded)
• Excel for Windows (desktop app)
• Copilot in Excel

Issue: I am repeatedly receiving the error message "Failed to fetch document context due to an internal error" when trying to use Copilot in Excel. This error has been occurring for multiple days across multiple sessions.

What happens:

1. I open my Excel workbook (.xlsx file)
2. I open Copilot from the ribbon
3. I ask Copilot to perform a task (e.g., write data to cells, read from a table)
4. Copilot responds as if it completed the task
5. Nothing actually happens in my workbook — no data is written, no changes are made
6. The error "Failed to fetch document context due to an internal error" appears

What I've tried:

• Restarting Excel (multiple times)
• Closing and reopening Copilot panel
• Signing out and signing back in to my Microsoft account
• Checking for updates
• Waiting several hours/days and trying again
• Force-closing Excel via Task Manager
• Starting fresh chat sessions
• Contacted Microsoft Support chat (they directed me here)

None of these resolved the issue.

Impact:

• I recently upgraded to a paid subscription specifically to use Copilot
• I cannot use the service I paid for
• Simple tasks like writing text values to cells do not work
• Copilot claims tasks are "done" but nothing actually changes in my workbook
• This has been happening for 5+ days

Questions:

1. Is this a known server-side issue?
2. Is there a fix or workaround?
3. How can I get this resolved or request a refund for a non-functional service?

Thank you for any help!