yeah mine is a 128GB. So I ended up using the PCIA slot with an adapter to a CF card that our maintenance team had. Worked like a charm so was indeed something to do with the USB itself.
After that, went back to the procedure of turning off the brake (opted not to delete the axis at this time!) and was able to then clear all the faults and move Mr. Robot in to an easier position to be worked on.
Thanks for the help!