Ah, so you're saying we're sending a "mixed message"? 0x9n is "note on for channel n", but when that's inside a SysEx it's a "Status Byte" (MSB is 1) and so considered an EOX.
Interestingly that "considered EOX" isn't dropped by MIDI Monitor but is processed:
...so treating the packet as two commands
F0 00 00 66 10 12
/implicit EOX/
90 65 7F
..which also explains why post-fixing the KM raw packet with an explicit EOX, as @Vladistone was, throws an "invalid" for the final F7.
Interesting...