I have 3 desktops, the desktops do not count on the poly-chain!
It starts with the next note if there is no more Desktop in the Chain to play it! ;-)
The 1st Desktop must have Poly-Chain set to ALL, and Midi Clock set to OUT, Midi Xmit = ALL
the 2nd Desktop Poly-Chain set to All, and Midi Clock set to I-O, Midi Rec = ALL, Midi Xmit = ALL
" " "
the last Desktop Poly-Chain set to Off, and Midi Clock set to IN, Midi Rec = ALL
And all of them need the same Midi channel