The subject behavior even happens after you configure Group Policy to not synchronize offline files during log on and log off.
Changes in Group Policy only alter settings for complete and quick synchronization of offline files in Synchronization Manager.
NOTE: Redirected folders are always made available offline.
After you configure Group Policy to synchronize offline files, Synchronization Manager automatically synchronizes your offline files during log off or log on.
NOTE: Complete synchronization makes sure that offline files are complete and current. Quick synchronization makes sure that offline files are complete only.
After you disable the policy settings for synchronization of offline files, Group Policy prevents synchronization of offline files in Synchronization Manager but still enables quick synchronization.
To prevent Synchronization Manager from synchronizing offline files during log off or log on:
1. Start / Run / mobsync / OK.
2. Press Setup in the Items to Synchronize dialog.
3. Select the Logon/Logoff tab.
4. Clear the When I log on to my computer and When I log off my computer boxes under Automatically synchronize the selected items.
5. If you desire a prompt before Synchronization Manager begins synchronizing Offline Files, check the Ask me before synchronizing the items box.
6. Press OK.
7. Press Close.