OK, i think I have honed in on the issue, and can duplicate it (or make it work) using TTS1, and a single MIDI track playing 1 note 4 times.  Start a new project delete all default tracks Add a TTS1 VSTi instance Add a MIDI track and set it to use TTS1 Channel 1, and select Clav as the patch Add 4 short notes in rapid succession (see screenshot below for details) using Piano Roll, all the same note Create an Envelope for pan, as shown below using jumps.