I thought they were sounding because - although notationally Dorico can tie a note from one voice to the same note in another voice, it will still re-articulate the note. I somehow thought Dorico had surmounted that problem. Was it supposed to sustain the tied note or did I misunderstand?
At the moment, ties between voices are not played back properly as a single note: unlike regular tied notes, which really are just a single event in playback world, tied notes between voices are separate events and at the moment they play back that way. Paul has plans to address this in the future.
Thanks Daniel, the ability to tie notes between different voices can solve a lot of ackward notational problems