I will try to put my experience with this matter. I've been following this thread almost since it started (over 1 year ago) hoping that Microsoft will fix their OneDrive app (which was working great at first and suddenly that app has been hell to work with). I was using onedrive to sync my data (over 230GB) between a Windows computer and a MacOS laptop. As the people in the thread have been saying, suddenly the app began to consume a lot of resources and not leave the files offline. Although Microsoft added the famous "Download all OneDrive files now" button, it doesn't work and the files are still online. And what's more frustrating: when you try to open a file online, it spends minutes trying to sync and download it.
I think I've waited long enough to see if Microsoft fixes the app and it doesn't look like they will and/or they want.
Solution: I have switched to Google Drive and it works perfectly the first time. And it doesn't leave your laptop consuming resources. I don't know how it does it, but you can already see that there is a possible solution, but Microsoft doesn't want to implement it.
Hope this helps.