your new playing technique is now MMportomento, right? If you hover over this p.t, you’ll see something like the screen below.
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Although the name of your new technique is MMportomento, the actual playing technique used is “portamento up”. Perhaps it’s clearer looking at the second screenshot showing the details of your technique.
The name of the actual technique is what appears in the Expression Map, not the popover text which is more the title. And it is there! You’re far from the first person to make this mistake – I also learned the hard way and Dorico doesn’t help by using the terms “playback technique” and “playing technique” rather confusingly.
I had suspected this and it’s what @gdball also suggested earlier on