A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
Hi David,
Thanks for posting in the community. We are happy to help you.
According to your description, I would like to know if the user opened the file from the OneDrive/SharePoint local folder (the left side of the File Explorer).
If not, please point it out and let us know.
If so, as she can open the files in the browser, please ask the user to click the "Editing" button and select "Open in Desktop app", Or try the following steps to open "problematic" SharePoint files.
- Run the related Office application first
- Click File> Open, select SharePoint, then go to the related site and open the file
If she can open these files in the Office applications, it means the situation is not caused by the files themselves, but by the sync app. I suppose she uses the OneDrive app to sync the SharePoint library to local. If so, please try to reset OneDrive, and then check again.
We look forward to your response. Thanks for your cooperation.
Sincerely,
George | Microsoft Community Moderator