This isn't common, but to fix it, go to your computer's system tray (if you use a Mac, go to the menu bar) and find the sync app. Select the OneDrive cloud icon. In the activity center, select More > Settings. On the Account tab, select Choose folders, check the boxes of the folders you want to sync.How do you automatically start OneDrive?
Step 1: Type OneDrive in search box, then click it on the result. Step 2: Open OneDrive settings, and check the Start OneDrive Automatically When I Sign in to Windows checkbox. OneDrive icon will display in Taskbar notification area again and start syncing OneDrive files to your PC.