Core Storage was introduced by Apple in Mac OS X Lion, providing new disk features such as Fusion drives and FileVault (encryption). Unfortunately, this technology causes problems for utilities like MacDrive, making most Core Storage disks to be inaccessible.
The first step is to determine if your drive is Core Storage. You can run the following command in Terminal on the Mac to check your drive:
diskutil cs list
If there are no Core Storage configurations, Terminal will say “No Core Storage logical volume groups found”. If there are Core Storage groups, Terminal will say “Core Storage logical volume group (Number Found).
MacDrive can access some Core Storage drives, as long as they unencrypted and recognizable as an HFS+ drive. Unfortunately, MacDrive can’t access Fusion drives or FileVault drives.
In some cases, it’s possible to revert your drive from Core Storage so that it can be accessed by MacDrive.
To check if your drive is revertible, run the Terminal command above, and look for the following line under “Logical Volume”:
Revertible: Yes (no decryption required)
If the “Revertible” line says “Yes (no decryption required)”, the volume can be reverted. There are several articles online for steps to revert the volume. You can also contact Apple for additional help.