Dropped Note Issue with Poly LP + SP (v3.1 build 672)

Hey there,
I just added a Slim Phatty to my Little Phatty Stage II for poly-fun and I installed firmware v3.1 (build 672) to both units.
However, I am getting the “dropped note” problem as the manual addendum mentions, but selecting “ALL NOTES OFF” does not solve the problem.

As I play a simple polyphonic (octavised) 4-bar progression, the note always drops out at the same point (even though note changes are played non-legato). I’ve noticed in some other rhythms that the problem doesn’t occur, but it seems to randomly happen with some different progressions and ruin the musical piece.

I currently have the midi settings as the poly-chaining video states, and the LP’s midi out port connected to the SP’s midi in port with a midi cable (maybe I should connect another midi cable from the SP back to the LP to make a loop as I’ve seen mentioned before??).

Another random guess is that my Slim Phatty has the Serial Number: 1109. Did I once hear something about SP’s under a certain Serial Number having some type of problem?

Any help would be greatly appreciated (So I can add more Slim Phatties!)

Regards,
David
NZ