WD Passport 1TB won't work on XBOX

WD External Drives WD Portable Drives
2

exFAT regularly does not work with gaming devices. 

Check the drive for problems on the computer.

How to test a drive for problems using Data Lifeguard Diagnostics for Windows

http://wdc.custhelp.com/app/answers/detail/a_id/940

See if the drive is seen when creating two partitions.