I mix my TSP with the detergent with a spoon. I have kept experimenting, and I think they come out better when I used powdered detergent than liquid.
I still can’t believe we have to do this.
But they make the powdered detergent in such a way that it is released over time, while TSP dissolves and rinses away a lot faster. At least that's the way I think it works.
Didn't the "old" Cascade release gradually? Otherwise it would rinse away and your dishwasher would be rinsing with only water for the rest of the cycle.