When migrating Excel files, a "KeyPoints" required field is added to the target.
When migrating Excel files from a Classic Site template to a Classic Site template and the file has both minor and major versions, in the target library a "KeyPoints" required field may be added to the Excel file preventing the file from being checked in. The field is set to "read only" and cannot be modified.
There is an error in the Microsoft API.
If this issue is encountered, please open a support ticket with Microsoft to have it resolved.