There are two common reasons why an Excel or Word file can be opened “read-only” using Web Folders, but cannot be saved back to the My Docs Online Web Folder location.

Folders other than the Group “Root Folder”
If permissions for the sub-account are set to “View Only” the user will be able to open, but not update or save an Office file.

Files in the Group “Root Folder”
The “root folder” is by design always “view only” for all users except for the administrator ID.

The solution is to create a folder to hold the files instead, set the permissions as needed, and move the files.

In general files should not be in the Root Folder, only folders.