Q: Mac Pro doesn't recognize external hard drive. It is not shown in Disk Utility at all. Drive formatted to exFAT. the Drive is

What shows in System Profiler under USB (assuming USB connection)?

OS X: About System Information and System Profiler - Apple Support

You should see both the chipset in the enclosure as well as the disk itself.

If the drive is powered by the USB bus then the bus on the MacBook may not provide enough power and you need a y-cable like this

http://www.staples.com/StarTechcom-1-USB-Y-Male-To-Micro-B-Male-Cable-For-Extern al/product_IM1DR6211?cid=PS:GooglePLAs:I…

This is the Mac Pro desktop forum. I requested your post be moved to the MacBook Pro laptop forum.

With use on a mac; exFAT needs to be formatted using a clutter size of 1024 or less.