Horizon 7.1 Blast Extreme nvenc problem

I have been testing Horizon 7.1 with GRID 4.2 & 4.1 for the last month. I am having a problem getting GPU based nvenc H.264 encoder to function. When playing a 4K H.264 video at 60Hz my primary core gets saturated with the Blast Desktop process. (CPU encoding)

Looking at nvidia-smi, I see the encoder at 0% utilization and the decoder at 45% utilization.

I have tested this with Windows 10 and 7.

Please advise.