I GOT IT! There’s an entirely new layer in X-keys that got added when I installed N6. I found it when I realized that I could now scroll down a longer list that had developed. Previously there were only 3 items on the list: Global, Nuendo 4 and Red. Once I found the Nuendo 6 option, I found that all of the previously non working commands were now in empty boxes! Once I copied the commands into those boxes, the commands started working!
Mystery finally and mercifully solved!