I know you have tried at least two different browsers, but Since the privacy and security settings in macOS are more oriented toward preventing incoming malware, it occurs to me the culprit might be related to a browser extension used in both the browsers you have tried.
- Try disabling any extensions in Safari and then attempting the upload
- Performing a safe boot should pretty well eliminate any blocking from your computer.
- On the off-chance the files may have been damaged during the transfer, have you tried reloading the files from their original source?
AI and DuckDuckGo searches turned up several similar posts involving Microsoft's One Drive, but none of those solutions appeared appropriate. I did find
this from CleanMyMac (which purports to be a sovereign cure for everything) but I have no experience with the product and would not suggest it, if it weren't for the 7-day free trial. It is also available on the
App Store where it gets mixed reviews.