A Microsoft file hosting and synchronization service.
Our business has this same issue where a file that is saved on SharePoint will have autosave turned on by default but then each day the file will go to AutoSave off when accessed and then asks to sign into OneDrive when turning AutoSave on. AutoSave will turn on, but it then creates a copy that lives at the personal OneDrive level. For instance, I will go into a folder that shows its path as C:\Users\ComputerUserprofile\OurSharePointDomain\SharePointSiteLibrary
When the file on this folder is accessed and AutoSave is turned off, our user will turn on AutoSave and then receive a prompt asking to Sign in to OneDrive - (Business name) or OneDrive with no other text after OneDrive
When OneDrive - (Business name) is selected, another prompt comes up saying "Just a moment. We're uploading a copy of your document. You will continue to work on the uploaded copy."
This then creates a copy that is the same file name with a (1) appended to the end. The files are the most up to date file format (.xlsx, .docx, etc.) but this happens to them each day.
Knowing this is a bug with OneDrive or how OneDrive interacts with SharePoint at least gives me something to tell them but can Microsoft really not address this issue quickly? It creates a lot of double work and paranoia of losing data as a result.