Extremely frustrating!
We have had several users on our team report that the AutoSave on Microsoft Word and Microsoft Excel in O365 keeps randomly disabling/turning off.
We have tried everything to remedy it but nothing seems to work!
For example, I have a Word document in my OneDrive. When I open that document using desktop MS Word application, AutoSave always seems to be OFF by default. To turn it on, it tells me I have to go to Adv. Options and "Allow Background Saves". When I do enable Background Saves, it then allows me to turn on AutoSave. However, as soon as that document is closed and reopened, all those settings have reverted back! It seems to do this 100% of the time.
I remember when we first switched over to O365 a year ago, this was not an issue at all. AutoSave seemed to work very nicely and was always turned on by default.