Pianoteq 9 as a VST plug-in in Dorico does not play the microtuned pitches notated in a Tonality System in Dorico. MIDI Tuning is set to 'Yes' in Pianoteq. None of the four options in Dorico Expression Maps - Auto, VST Note Expression, Detune, or Pitch bend - work. Changing the Playback Template doesn't help.

However, Pianoteq 8 works, as always. This implies that in Pianoteq 9, the VST tuning method that Dorico uses is broken. Or perhaps something now goes wrong when Pianoteq 9 is opened as plug-in in Dorico.

Pianoteq 9.1 does respond to MPE, MTS-ESP and single-note-MTS tuning in a DAW, using external apps, plug-ins and controllers. As far as I can tell,  VST tuning in Dorico is the only microtonal feature that has stopped working.