Cannot see USB drive

I have a ReadyNAS NV+ that I have been using for about 3 years. Recently it has been giving me a lot of various problems (configuration issues, unable to access it through Frontview, unable to upgrade firmware, etc.). After playing with it for a while I finally decided to backup all of my data and do a factory reset to try to get things running cleanly again.

I did the factory reset and the device came back fine. I was once again able to access the unit via Frontview. I upgraded the firmware to 4.1.12 and thought all was good. However, I am now not able to see or access my 1TB USB drive when I plug it into the USB port on the device. When I plug the USB drive into the device, I see the message that a USB drive has been connected on the LCD in the front of the device. However, I cannot see the USB drive when I try to configure it in the "Volumes / USB" tab in Frontview.

I have tried reformatting the drive (FAT) using my PC and I have tried to plug the drive into the various USB ports on the device .... no luck.

Any suggestions on what I should do next to try to get this running?

Paul