I have a brand new WD Black 6TB SATA drive which is unreadable in my BlacX 5G dock. The drive shows up fine connected inside the computer case via SATA connections. But when connected via the BlacX 5G's USB 3.0 connection, Disk Manager says that the disk is "unknown" and "unallocated" and you can't initialize it. Oddly, I can initialize it, format it, and use it mounted inside the computer via SATA connections. Then, if I remove it from the case and put it into the BlacX dock, it again shows as "unknown" and "unallocated".
By the way, my BlacX dock works just fine with other SATA drives