Notation issues

Did you get this music into Dorico by
a) step-entry within Dorico?
b) real-time MIDI entry within Dorico?
c) MIDI import from other software?
d) MusicXML import from other software?

  1. Why not just use an actual trill?
  2. Is it possible that the sample just isn’t speaking quickly enough? If so, you might be able to adjust the attack of that sample, depending on which sample library you’re using.
  3. Turn on View > Note and Rest Colors > Voice Colors and take that screenshot again (the one with the rests).