I have an Excel file shared widely on SharePoint. Most users open the document with Excel Online. A couple times, I've seen when a user opens it with the Excel client, it then locks the file for editing for other users. As soon as that user closes the Excel client, the lock is removed. Check-outs are not required on the Document Library. I do want to allow co-authoring.
What can I do to prevent this locking? Is there a way to block anyone from opening the document using the Excel client?