MIDI THRU has been improved in the latest software. But, the problem before was that it worked most of the time but dropped out during program loads.
Whereas, you are saying it does not work at all, which is different.
Some MIDI equipment requires power from a MIDI output, which is not supported on H9 before serial number 16329 – I'm not sure if this is the case here (can't tell from Marshall manual).
Have you used the H9 MIDI out with anything else ? There may be a hardware problem (unlikely, but possible).
