
Hello! Stephen. I'm glad to assist you with this.
This usually ties into sync issues, caching, or limitations in how co-authoring works across platforms.
You can resolve this by clearing Office Cache and OneDrive Credentials. Here's how:
Sign out from Excel and OneDrive.
Clear cache files (on macOS, you can sign out and back in; though Windows paths differ, the principle is the same).
On Windows, for reference: clear %AppData%\Local\Microsoft\Office\16.0\OfficeFileCache and remove OneDrive/Office credentials from Credential Manager.
Reinstall or update Excel if needed.
While specifics vary on macOS, re-signing in and ensuring the app is fully updated often resolves this.
Best regards,
Kimberly