So I was working on this awesome model for a project in Daz3D 
and I kept getting this:
I was thinking that the NVIDA IRay didn't like my new Macbook. Doing a quick search and I came across this solution by tonyjas46_1cccd9144e:
If you get a transparent render: For low angle shots below the ground plane remember to switch OFF the Draw Ground option in the Render/Environment panel. (Gets me every time)
Go to Render -> Render Settings -> Environment and Click Draw Ground to Off.
This allowed me to then render and get the final output. 