What does the layer/key mixer stop working at 6 inputs?

I have a problem. Using a variety of polygon masks, power windows and qualifiers using multiple nodes, I am then mixing them all into one layer mixer and key mixer so I can then apply my grade to all the areas at once. I am running into a problem where only up to 6 inputs actually work. Inputs #7 and #8 do not work at all. I even tried swapping things around and the non-working keys work fine, if I disable some other inputs so I only have a max of 6. But no matter what I try to do, additional inputs for the layer and key mixers stop functioning after 6 inputs. Anyone know what's going on??

I don't know the answer.

Can you combine few shapes in one now and consolidate?

node graph fixed.PNG (130.15 KiB) Viewed 1142 times

I was able to solve it. I combined some of the node keys prior to integrating them into the main key mixer to keep the number of inputs limited to 6 -- and that worked.

That's a lotta key inputs.