Seagate Backup Plus Slim External USB 3 Hard Drive Not Working with Mac Pro

Hi, I have just purchased a brand new Mac Pro. I have three 2 TB Seagate Backup Plus Slim External USB 3 hard drives that just don't jive with the new Mac Pro's. When the drive is connected, I cannot access the drive, read/write or even format. Finder completely locks up and the drive cannot even be force ejected. When I try to format, Disk Utility either spits out an error that the drive cannot be read, or simply locks up. This happens regardless of the OS on the Mac Pro. I am currently running 10.10.2

I have ruled out an issues with the drives, as I have tested all of them on a variety of systems and OS's, including Power Mac, Mac Book Pro, PC, OS 10.7, 10.8, 10.9 as well as on Windows. I have tried formatting in every file system including Mac OS Extended, Mac OS Extended (Journaled), NTFS and exFAT. ALL other systems have no issues with the drives. Apple has replaced my Mac Pro with a brand new one and the drives still behave the same way. Furthermore, I have tested the drives on three other Mac Pro's at work and they all reject the drives. So, on their own, there is nothing wrong with the Mac Pro, or the drives. However, the configuration of them together is wreaking havoc.

I have contacted Seagate, and this was their response:

The most recent version of the Backup Plus drives use the USB Attached SCSI (UAS) standard to increase transfer rates. It's possible that the drivers being used currently on your Mac Pro are having issues using this feature with the standard USB 3.0 drivers installed. I would recommend contacting Apple to check for any driver updates or see if they any suggestions for issues involving drives using UAS.

I have also started a case with Apple Support (Case # 755934373) and am waiting to hear back regarding Seagate's response. I've spent DAYS trying to troubleshoot this and am now at a complete loss. If anyone has any ideas, I'm all ears (or eyes in this case).

Thanks!