@ulrik Blinded by the MIDI SFX plugin option I never thought MIDI would be supported when exporting it without. Turned out I had to export as SFX Plugin, not as MIDI SFX Plugin... even though the plugin relies on MIDI. This works at least on Windows in Steinberg/Nuendo and VST3. Now I'll figure out if this is also the case on AU mac...

I suppose MIDI SFX Plugin is for pure MIDI plugins then, not supposed to handle audio at all?