Support for the old OneDrive for Business sync app with SharePoint Online will end on January 11, 2021.
If you see this icon on the right corner of your taskbar, read this article to learn more.
Consider the following scenario.
You upgrade to Office 2016 on your computer.
When you use OneDrive, your libraries stop syncing, and the icon overlays don't appear on synchronized files and folders.
To resolve this issue, follow these steps:
Manually start the OneDrive desktop app through the Start menu.
Restart the computer.
NOTE: After you restart your computer, you shouldn't have to manually start OneDrive for work or school again. The OneDrive desktop app should start on its own and then sync your libraries.
This is a known issue. This issue occurs because OneDrive doesn't restart after you install Office 2016.
Still need help? Go to Microsoft Community.