Hi @LaraLou ,
Welcome to Q&A forum!
Please refer to this offcial article to update your Office to the latest version.
Besides, I have the following information want to confirm with you at your convenience.
- When did this issue start? Have you install any other programs and updates before the issue? Such as third-party Add-ins, please go to Insert>My Add-ins to remove all for a check.
- How about other Office apps? Such as Word and Excel, do them have the same issue?
Since this issue occurs randomly, and Office for mac does not have the Repair option, if the above do not work, I suggest you try to uninstall, reboot and reinstall for a check.
Links:
Uninstall Office for Mac
Reinstall Microsoft 365 or Office 2019 on a PC or Mac
Any updates, please let me know.
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