Hi Eric,
remember your Novation RemoteSL MIDI templates? and that we found out that MIDI CC reset at the top each time, and that sysex commands were better for 'setting'? (parameters) ?
actually there is another matter here with this that i remember, that might have some bearing: if you want to use a sysex command - say, to switch Local Off on any given Track/Part (which is what i was doing one time, so that i could have some QY sounds -drums-, whilst sequencing an exterior sound module on other Tracks) - i had to set up the sysex messages at the top of one of the SONGS, so that i could have the MIDI Local Off on those Tracks, in PATTERN mode.
so i'm thinking, maybe, these Bank/ProgramChange messages need to be sent to the QY on Song tracks, for them to be effective in the Pattern mode. you were saying there were 8 + 16 = 24 tracks. but it is still just 16 midi channels, and the Pattern mode voice assign uses the Song mode assignments (1-8 or 9-16), and maybe this has some bearing here. (i can't remember if there was a way to assign voices via sysex instead of BankSel/ProgChng)
(soz, response is a bit convoluted .. )