RemoteFX install problem, what else should I try?

This question seems to have been asked several times, but none of the answers seem to fix my experience.

#1 - My CPU support SLAT

#2 - dxdiag says I have DirectX 11 and WDDM 1.2

#3 - I have Remote Desktop Virtualization Host role enabled

In Hyper-V manager Hyper-V settings, physical GPU, the GPU combo box is grayed out.

So I'm left with the question, what else is blocking use of RemoteFX?

Thanks!