When opening multiple spreadsheets, Microsoft Excel shuts down. Changes are not saved, and work is lost.
Microsoft Excel can lock up and shut down due to performance limitations of a workstation or server, for example, a lack of resources when large files are opened simultaneously.
If files are opened directly via OneDrive Online, and not first synchronised locally, Excel will need to retrieve the document priority opening it. Depending on how many resources Microsoft Excel is already using, retrieving the document can cause the application to freeze and close.
IT will need to review the performance of the workstation or server to determine whether improvements can be made. For example, increased RAM, or a device replacement.
If not using the OneDrive sync app, it's recommended to install it as this will first synchronise the file to the computer before opening Excel, decreasing the resource load.
The FYI Desktop app can also be used for document editing independently of OneDrive. Refer to Opening, Editing and Finish Editing Documents with FYI Desktop App.