Why can’t I bus power my FireBox on my MacBook Pro?
Apple implemented "Over-current Protection" in the hardware of their MacBook Pro. Upon initially plugging in your FireBox, it will draw a brief surge of power which will trigger this protective circuit, preventing it from properly installing. Plug in your interface via its supplied AC adapter before connecting it to your MacBook Pro. Once the interface's sync light turns solid blue, you can unplug the AC adapter and use it as you normally would.