I used a lot of time to have the sequencer and the synth to behave the right way.
The first time I did it, it should work, but the note was "hanging" on the last note I hit, let's say Bb even if C was pressed. I found a work around with a feature called "Last note" out on a CV and this controls the Oscillator pitch.
These small differences that chances the whole thing, is different from DAW to DAW. So maybe one VST can't while another VST sees it another way and it works.
....I am pretty sure Michel Geiss didn't used a "Last Note" scroll down menu, when he connected his Matrisequencer to Arp 2600