When I select a full measure with tuplets it will also select the first tuplet in the next bar. See GIF:
I’m not able to reproduce the problem on my machine. Try temporarily clicking a different tab (Engrave mode or Write mode for example) then switch back and see if you’re able to select the notes properly. This works for me sometimes when Dorico is a little glitchy.
I suspect that the last tuplet of that bar is actually a sextuplet that Dorico has split across the barline, so it is in fact a single tuplet.
I could imitate the problem. I would insert a tuplet of 3 eights at the 4th beat of the measure and also a tuplet of 3 eight of the 1st beat of the next bar. Accidentally I have insert a tuplet with the ‘quarter’ note selected. It makes now a tuplet from 3 eights of the 4th beat and a tuplet of 3 eights at the 1st beat of the next measure. Exactly what I want I thought…
Yes, so it’s not a problem, but rather exactly how Dorico is supposed to work. It can intelligently split a tuplet over a barline, but it is still a single tuplet.
Sorry for my wrong word choice. Sometimes it is difficult to see of it is a problem or an intelligently feature.