1. Check the settings on your OneDrive. Make sure that the service is enabled and authorized to sync with a third-party if applicable.
2. Confirm that the files you want to sync are in the shared folder in OneDrive.
3. Log into your third-party cloud storage account and make sure that it is also authorized and enabled to sync with OneDrive.
4. Try a manual sync between OneDrive and the other cloud service by running the sync operation again.
5. Confirm that you are using the latest version of OneDrive. If not, update to the latest version.
6. Verify that your internet connection is working properly. If not, try resetting your connection.
7. Try clearing cache and cookies in your web browser.