Hi Michael,
Greetings! Thank you for posting to Microsoft Community.
If your issue is only on one file, share your file to us to check the file.
If your issue is on all the excel files,please try the following steps to repair your Office, then check again.
Go to Windows Settings> Apps> Apps & features> find the Microsoft Office product> select Modify> then choose Online Repair. After repairing, please restart your device and run Office applications to check again.
If the situation still happens after repairing Office, please install and run the Office uninstall support tool to completely uninstall the existing Office applications, then reinstall Office and check again.
Best Regards,
Snow Lu