I have a Mac Pro originally 4,1 but flashed to 5,1. I have an Isight I recently purchased for Zoom meetings. When I connect the Isight to my MacBook Pro it works, however when I connect it to my Mac Pro it doesn't. The firewire connection is fine. I use a FW400 to FW800 adaptor to connect the camera to the desktop but nothing, not detectable, not showing up. I've tried multiple ways to connect the camera even purchasing a firewire 400 to USB adapter and nothing. I'm running MacOS Sierra. Any help would be welcomed.