Had a moment to read over the docs and noticed this:

https://image.prntscr.com/image/mRvZhdOGRiahblCodhyNbQ.png

Assuming it's referring to the Private key column at /keys, it doesn't seem to have been generated when the Site key was generated:

https://image.prntscr.com/image/aBa67jytSXKHWxaX0tGjKA.png

And this is the error when trying to add a new key:

https://image.prntscr.com/image/qMXCrVrSRMSamQdhnppPSg.png

Work in progress or a site hiccup?