File Upload/Download Errors

Backing up with SharePoint is one thing, restoring is quite another. Had same problems. We have working solution at another location using <$50 synchronization software by Syncovery.
I evaluated every major program of its kind, and it hands down hits all the buttons with selective backup / copy, recovery and file versioning, plus it has option to preserve last modified folder date. We back it up to the Business OneDrive but don't need or want the sluggish OneDrive client. Might take a while to wrap your head around all the options, that said support for the free trial and after was fast and expert. Check it out. <commenter is not associated with the company, not an ad>
With all due respect Microsoft, this limitation is asinine. "Welcome to Hotel Sharepofornia. Such a happy place..."they can "check in, but they can neeever check out." Not all at the same time anyhow.