"Other people are editing this document." How? I have never granted anyone else access to it.

[ricecrispies]

I have a Word document that I keep in my OneDrive storage. When I open it, I get the message "Other people are editing this document", and get asked if I want changes to be made immediately. the thing is, I have only granted other people access to a tiny handful of the files in my OneDrive storage, and certainly not to this particular document, which is a personal journal. I haven't got the document open on any other device. So who else is editing the document?