Megabase and One Drive auto backup and synching

I tried to do an opening report in Chessbase and got a curious message that my reference database was missing. I look in the bases folder and indeed everything is gone. Now there should have been a couple of large databases like Megabase 2019 and 2020 there. They were there ten days ago when I looked at the directory. So what happened?

About a week ago I was poking around in One Drive which is a Microsoft service which comes with hotmail and possibly Microsoft Office. I noticed that it was backing up my chessbase folders which reside in my documents folder because of accepting the default installation. This seemed wasteful as it involves many gigabytes of data which I have backed up and could download from chessbase.com if it ever happened that I needed to reinstall it. I originally bought a deluxe version of chessbase 10 from Strategy and Games in Toronto and registered it and have been getting updates from Chessbase for the last few years. They always have a ridiculously inexpensive upgrade price to the latest version and I usually take them up on it. Anyway I applied brute force and deleted the One Drive files which backed up the Megabase files. And so the deletion propagated back to my computer and the files were removed from my computer. Argh!!!

It took a couple of minutes to restore the Megabase files and there don't seem to be any issues but I shut off the Onedrive backup function as it seems dumb to be moving so many gigabytes of data to the cloud when I could use my normal backup files to restore if it were ever to be lost from my newish computer.

One Drive and Dropbox and many of the 'cloud storage' schemes have behaviours like you describe - they seem to think they "own" the bloody files and sometimes will just remove files here and there and everywhere. I use Good Drive to keep copies of things and I absolutely AVOID using their drive sync software for the same reasons as you have found. I dont have any Apple products but I think they also like the idea of managing your files everywhere (or nowhere as it sometimes can be).
Seriously, some software developers are complete idiots and those who manage such projects even bigger idiots for imposing their way of working on every customer of their software.

I use dropbox mostly to share files but they mostly backup files which are in a dropbox directory already and not files that I wasn't intentionally backing up.

I suspect the issue comes from Microsoft Office. At one point I did notice that some of my files were being saved to the cloud through One drive but I really had no idea that they were mirroring what I was doing on One Drive back to my computer. I back everything up compulsively but am not necessarily keen on all of my files being online and dependent on someone else's security. Anyway, I think I have killed that backup and synch for now until the next update changes the options on me. I would be more upset if I was still creating my own custom database of games from online sources. These days I just pay the money every year and upgrade to the latest and greatest and download updates through the program.