You may want to make sure the drive receives enough power when plugged to the eSATA port; you may also test the drive in a SATA port just to make sure it works properly. A firmware update may help too.
Problem was eventually traced to a faulty controller on the HDD. Windows and RST were able to identify the drive correctly, and the drive appeared to be ok, but failed when trying to write with an unknown I/O error. Replacing the drive's controller (via warranty repair) fixed the issue, and now it's working as expected.