In my case, all your setup worked perfectly, except for the confirm button, I had it set up on Enter and it seems to only work using Space Bar. Do you have insight on this by any chance?
Edit: Also, I can see that if the mouse is still hovering another button and I use the arrow keys, not both will be set as “hovered”, yes Space Bar only works on the one I move to with the arrow keys, but It could cause confusion.