While DeviceLock Administrators feature is enabled, network drives and physical ports of a computer are blocked regardless of effective access permissions. The DeviceLock Service process ('dlservice.exe', or 'dlservice_x64.exe', depending on OS architecture) cannot be seen in Task Manager.
The behavior is a part of the DeviceLock Administrators protection. When DeviceLock service terminates unexpectedly, DeviceLock driver locks any activity that can lead to data leaks.
To return DeviceLock permissions to normal, reboot the computer. If the problem repeats, try disabling anti-trojan software that may cause DeviceLock Service to crash, and contact DeviceLock support.