Autosave on Office Applications with OneDrive not working as before from "Big Sur" onwards

I have three Macs: one running Big Sur, one running Catelina and on running High Sierra.

I have a Microsoft Office 365 subscription for Word Powerpoint and Excel and am using OneDrive to store all my data, syncing between my OneDrive folders in the Cloud and the local OneDrive folder located on my Macs, in location username/onedrive.

When I am online, any file I create and save on the local OneDrive folder is automatically synced to the OneDrive folder in the cloud - and this in turn syncs with all my Macs local OneDrive folders.

This all works well

However, the option to AutoSave files as you work on them does not work on the Mac running Big Sur, yet does on the other two Macs

On my older Macs, when I open an Office document on my LOCAL OneDrive folder, or create a new document and save to to my local OneDrive folder, then the Autosave function is automatically on, so ensuring changes were autosaved to the local file and then synced up to the cloud and then across my other Macs. This is still how it works well on both my Macs running High Sierra and running Catelina.

But on my Mac running Big Sur, I get a message saying that, for Autosave to be switched on, I need to direct my file to be saved to the online Cloud OneDrive folder, and not to the local Onedrive location which I want to save it to. Indeed if I open up any of the thousands of word and powerpoint files I have on my local one drive folder, autosave will not switch on on any of them, unless I repoint each one to save to the cloud, file by file!

I can reconfirm that "Use Office Applications to sync Office Files I Open" is enabled on my Mac in OneDrive Preferences, and the option "Turn on AutoSave by default" is switched onin the Office for Mac application.

I have tried deleting the Onedrive app, renaming the local one drive folder to a dummy name, then reinstalling the Onedrive app (downloaded from my 365 online account) - which then creates a new Onedrive folder locally on my Mac, syncs all my thousands of files down correctly from the Cloud (as I want it to), and so installs properly. But the Autosave is still not working as it does on my older macs

I have also tried deleting and then reinstalling the Office 365 apps from theOffice 365 web page - again this makes no difference.

Why will Onedrive autosave not work on Big Sur like it does on earlier Mac OS versions - it is a huge problem for me.

I don't want to Autosave to the cloud by default as I work, as I am often not connected to the internet and am working on my files stored locally on my Mac. I want Autosave to be on to protect the work I am doing as I go, autosaving to my local folder as it always has before Big Sur.

I want to save my files to my local OneDrive Folder, so I can work offline. It always worked this way in the past. And it still does on my two older Macs running Catelena and High Sierra. But on my Mac running Big Surrey autosave says it will only work if I point to save my file directly to the cloud first (which then syncs back down to my local OneDrive folder). Clearly this cannot work if I am offline, so is a real step backwards from how it used to work (and still does on my older Macs)

Is this a “new feature” that Big Surrey requires of OneDrive? It is a terrible feature if so. Can it be reversed or switched off? I want to save to my local OneDrive folder as I work mainly offline, and I want to have autosave working when I work…

Any help or ideas would be very welcome - thanks

Hustiniano