The Xbox controller is wired.
Okay, it seems as though there are some bugs with Unity's Xbox controller support. Did you perchance have two or more controllers attached to your PC when playing?
Yes, i have 2 controllers connected both Xbox
Ah ha! So the bug is that when multiple controllers are plugged in, the Trigger input is summed from all controllers which results in zero. I can put a work around in so that it only detects from one controller.
Thanks for your help with this!