Sorry for the delay in replying, I was away from the desk all week.
I manged to get the component machined in the end by using a longer cutter in the machine and I scaled the height of the model down by a few millimeters which meant I could do the whole surface in one go rather than splitting into layers.
I know this isn’t the problem directly solved but it seems like the issue is with Genio anyway rather than what’s happening in Rhino first.
Thank you all for your help and contributions!