Q: iBooks can't see my tablet to proof

I've built hundreds of digital publications but iBooks has NEVER been able to see my tablet. I unzip my epub every few weeks and attempt to sync as a proof and it refuses to see my tablet or phone. I can proof my books on a coworkers machine but my copy of ibooks does not see any ios device. When I plug my tablet into my mac pro it automatically loads up itunes but ibooks can't see it.

I've tried the following:

• Signing out of both ibooks and itunes and sign back in with the same ID

• Different USB ports both on my mac pro and on my monitor

• Different USB cables

• Different books, all of which has passed 3.0.1 validation

• Different user accounts on the same machine

• Running the latest OS on both the tablet/desktop

• Reinstalled a new OS multiple times

• This error run across the last 2 desktop operating systems.

• I'm running the latest version of El Captain with the same problem

• Tablet is running 9.3 but it was buggy long before I opted into the beta

Of course I know the difference between adding the .epub extension and a compressed version of the same book. ibooks needs the uncompressed version with the .epub added manually. Although for the sake of being thorough I've tried both multiple times.

If connect my tablet to a coworkers machine it works perfectly fine. He can sync the same epub with my tablet.

I've spent countless hours on the phone with Apple who were not even close to understanding the issue. In the meanwhile all I can see is a blank wall:

Any suggestions? I think I have a lemon of a machine.

ibooks 1.4(1099)

ipad air A1474 - 9.3

Mac Pro Late 2013 - 10.11.3