OneDrive mysteriously stopped working on my Windows 10 laptop. I have no idea what went wrong, I tried reinstalling it even though it’s now part of Windows 10. Nothing worked. I finally came across this post and wanted to repost it in case it ever disappears. My situation was the same, the GPO setting was unset, which should have had the same effect, but I had to disable it to get One Drive working again.

User ‘pirwen’ posted the solution that worked for me at this link in the Microsoft Community.

“I remembered seeing an option to prevent the usage of OneDrive via the Group Policy editor, seems that there is also an option to force enable it. Here are the steps I followed:
On your keyboard hit Windows Key + R to open the Run dialog and type: gpedit.msc and hit Enter to open Local Group Policy Editor.
Next navigate to Computer Configuration\Administrative Templates\Windows Components\OneDrive. In the right panel, double click Prevent the usage of OneDrive for File Storage.
Then here instead of selecting Enabled (as many tutorials suggest to disable OneDrive on Windows 10) I selected Disabled, and saved my changes. This option was originally unset, which should have worked just as if it was disabled, except it didn’t.
After doing this I opened OneDrive again and got a notification for an update. After a few seconds it opened, and was finally working again.”