This drive is installed on MAC Pro 2012 (12 core) running MAC OS ver 10.12.6. The drive disappears from the desktop and also Disk Utilities. The drive was purcahsed from OWC in 12/2017. Sent back to OWC and they say drive is ok. Is there a setting needed on the Mac or some HGST utility that is needed. Boot drive in 5400 internal HD
Have you try to change the SATA cable?