Two extra points. When installing the DMU, do not install the software on a device in which the Check Point Endpoint Client is loaded. We use a separate device that does not have the endpoint client installed.
Second, although the entire drive doesn't need to be fully encrypted, the encrypted volume for which you are trying to recover data needs to be fully encrypted. If the device was in the middle of encryption and the device failed, you need to initiate recovery procedures to remove encryption from the device to gain access to that data.