So a slight update.
I am now finding that some of the Windows 7 devices we are able to Inspect but these have not had the SU3 update installed yet.
So it seems to be inconsistent. All devices have the same agent and all are from the same build image.
I have not yet found a common demonitator between the ones that work and the ones that don't.
Will keep digging to see if I can find anything that is similar on any of these devices.