I have 2 iPhones connected to my Mac via a TBD, and I've also tried connecting my personal iPhone directly to my MBP with and without the TBD. But when I open Xcode, there are no devices listed, etiher in the targets menu or in the device manager (http://davbeck.s3.amazonaws.com/no_devices/a.png). iTunes doesn't see them either. System Profile does see them though (http://davbeck.s3.amazonaws.com/no_devices/b.png).
I've tried unplugging everything, plugging only a single device in directly, restarting Xcode and rebooting OS X. It seems like it correlates with updating to Xcode 7.1.1, but I can't say that for sure. I've also tried the latest 7.2 beta but get the same issue.