OneDrive deleted local files and started syncing old files !

Always Save everything on a separate hard-drive.

It's the same with me. I connected my device to my OneDrive. I have backed up my desktop a month ago so my updated files are the ones on my local. When it synced, the files on the cloud replaced the files on my local and the updated versions don't show up on version history (because they're not history! they're more recent!) so there's no way to restore them. It's also not available on the trash bin of either OneDrive and local desktop.

Someone fix this! Happened to me twice. Wish there was simply no sync option if it's not working right

I raised this problem on April 3rd 2020. Following days of downloading & uploading, re-installation, and the location and deletion of multiple copies that OneDrive generated, my own system now seems stable. 🤞 However, given that other users, such as Aiden7 today, are still newly encountering these same problems, it seems that I could be plunged into a similar crisis at any time in the future.

As I've said before, most of the world doesn't have the kind of data speeds available to Microsoft employees.  I must say I was very fortunate in my decision to use OneDrive ONLY as a location for multiple backups and long-term storage. It does create difficulties. e.g. many tools and daily actions, such as Windows "File Open", go to the OneDrive directory first. Microsoft think that OneDrive should be the main data repository, I suspect because this would generate more revenue. 

In my own case, my C drive is an SSD so I was using my D drive to hold all my documents, including the OneDrive folder.  I am wondering if that could have something to do with it. Windows and OneDrive seems to want to keep trying to default to C drive and it's really quite difficult to change this. It shouldn't be difficult. After all, the vast majority of Microsoft customers know as much about the inner workings of a computer as they do about Astrophysics, and many will have (much smaller) SSDs as their C drive.

In any case, it's about time the OneDrive team had a proper look at what is being reported in this (and other "closed" threads), rather than insisting that OneDrive doesn't delete files without authorisation. I worked in IT for many years and I'm well aware of the temptation for IT pros to say, "That's impossible!" when users report a fault.

PS Wouldn't it be wonderful if OneDrive used easily searchable text to flag copies it had made. At the moment, it adds " - copy" to the file name. Has anyone ever tried to search for that term? The presence of spaces makes it even worse. Why not add something utterly unique like"-OneXDrive", also without any spaces?

In case anyone was curious, this is still happening in December 2020. Bought a new laptop, everything uploaded over just fine, then 1 week later my one drive has reset to what it was a month ago. Hours of work lost. I cant believe this has been happening for 6 months, with no response or fix from Microsoft.

I share your concern. I use OneDrive as a place to manual backups and some bulky stuff I'd just prefer to keep securely in the cloud.

I think that Microsoft want, expect, and therefore really try to FORCE, all users to use OneDrive as their working data source for everything. Whilst this may be a great way to work if you have a 10Gbps internet pipe, most mortals like us have to make do with download speeds of around 8Mbps to 80Mbps with upload speeds only about a sixth of that. 

When OneDrive do a major update, I suspect that staff are think it's safe to assume that the OneDrive data is the the most up-to-date and that users don't really use their hard drives for anything.

They make the same kind of assumptions such as C:<user>documents will always be the location of the Documents folder, even when you have an SSD with only enough room for Windows. (In my case, my C drive suddenly began to run out of space when I decided set some OneDrive folders to "local". At that point, I hadn't realised that OneDrive had taken it upon themselves to delete my D-drive data and change the system users folders to the C drive.

I wish Microsoft would come clean and admit they've made a mistake that has affected lots of their customers. I've fixed my setup now, but, unless OneDrive staff recognise their error, will it happen again?