Hah, that's a safe question. I'll admit that I am a bit of a midi newbie. The last test I ran was with the file you attached. I have everything running across a Quadra Thru splitter (even bypassed it just to make sure). Keys, Bass and Beats are set on channels 2, 3 and 10 respectively.
With each macro I attempted
-Only Zxx parameter changes in pattern with MPT channel assigned to Midi I/O plugin
-Same as above with added Instrument assignment number to pattern. Instrument linked to Midi I/O plugin and midi channels assigned to each Volca.