
Dear Andrew Powell,
Thank you for posting your question in the Microsoft Q&A forum.
Based on the information you have provided, it looks like you are having trouble signing in Excel on iMac.
Here are some potential solutions to fix this:
- Check your internet connection or try using another one.
- Restart your Mac then try logging in again.
- Reinstall Excel and try logging in.
- Remove Office license files ( follow the guidelines How to remove Office license files on a Mac - Microsoft ) then log in again.
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