Hi,
I am not familiar with this type of behavior, but it may be a file association issue: The user's system might incorrectly associate .xlsx files with a text editor or other non-Excel application. Check the default file association for .xlsx files on the user's machine. Ensure Excel is selected to be always used when opening .xlsx.
Other causes may include group policies and restrictions made by the IT dept., but it may not be the case as other users can open it. Check also if Excel is properly installed and not missing any components.
It seems more of a user's local environment or system configuration problem. Consider opening a ticket with OneStream Support, stating some context / share screens, including the IT team from the client as well.
Thanks
Ioana
