So I've been using my Taranis and Evolution with FPV Freerider on a MacBook Air, I prefer to use the evolution as it easy to transport and nice and comfy to hold, but Freerider has just stopped recognising it.

I've tried the old powercycle trick for the both the transmitter and Mac, looked all through settings to see if usb drivers need updating (used to using to windows) searched the web but can't find any answers... any ideas on how to get it working again ? 

Hmm well no I don't really have any ideas, I haven't heard of anyone else having the same issue. One thing is for sure and that is FPV Freerider itself hasn't changed (it doesn't use automatic updates). Perhaps your Macbook has received some kind of update. Did it just stop recognizing it all of a sudden?  Do you see any movement on the little circles as you go though the Calibrate Controller procedure in Freerider? The other thing I guess might be if something changed on the transmitter. Make sure you have Joystick mode selected on the transmitter (not USB mass storage).