Additional file-related features and issues within Microsoft Teams for business
Based on your description, the Excel file is stored in the SharePoint document library behind the Teams team. The fact that the missing content can sometimes be found in Version History suggests that the changes were successfully saved at some point, but a later version may have overwritten the current file. However, if the missing changes sometimes do not appear in Version History at all, this could indicate a different issue related to saving, co-authoring, AutoSave, or synchronization.
I have seen reports of similar behavior with Excel workbooks stored in Teams/SharePoint where users found that data disappeared from the current version while an earlier version still contained the changes.
When this happens again, I recommend checking the following before restoring the file:
- Open Version History and compare the versions immediately before and after the changes disappeared.
- Review the Modified By user and timestamp for each version.
- Check whether multiple users had the workbook open or were editing it at the same time.
- Confirm whether the file was edited in Excel for the web, Teams, or the Excel desktop application.
- If the SharePoint library is synchronized with OneDrive, check for any sync errors or conflicts and determine whether users are editing a synchronized local copy.
- Verify whether AutoSave was enabled and whether any upload, sign-in, or synchronization warnings were reported by Excel during the editing session.
If the missing changes do not exist anywhere in Version History, I recommend involving your Microsoft 365 administrator. They may be able to review SharePoint or Microsoft Purview audit logs to determine whether the file was modified, overwritten, restored, or affected by a synchronization issue.
If you're unsure who your IT administrator is, please refer to How do I find my Microsoft 365 admin? - Microsoft Support
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