I assume this never got fixed?
TORAIZ SP-16 : Please make MIDI tracks fully polyphonic
It is not possible to extend the length of a note to overlap a note after it, so you cannot program slides on monosynths that only slide in this legato manner... and chords will be cut off when the next trigger comes on. You cannot offset individual notes of a chord. Every note trigger on the sequence will stop any notes playing before it...
It is possible to work around this by using another track set to the same MIDI channel but it's not ideal.
Please make the MIDI tracks accept overlapping notes and allow us to play and record chords with the pads in Scale mode!
With this a piano roll view should be added so we can easily see lengths of MIDI notes in a sequence.