MIDI Message Modified with HD Pro X

[sbmech]

I have a HD Pro X with Flash Memory at 2.62. 

 

I control the HD Pro X with MIDI, and the MIDI setup has worked fine in the past.  I recently added a Boss DR-880 at the end of the chain (everything else is the same as it has always been):

Mastermind GT -> Voodoo Lab GCX (MIDI channel 16) -> Voodoo Lab Control Switcher (MIDI channel 16) -> HD Pro X (MIDI channel 2) -> Boss DR-880 (MIDI channel 15 drums / 14 bass)

 

The Boss DR-880 requires Sysex messages to be sent for start / stop / continue.  Here are the exact messages I'm sending from the Mastermind GT:

Start F0 7F FA F7

Stop F0 7F FC F7

Continue F0 7F FB F7

 

The Sysex messages were not working at first.  When I removed the HD Pro X from the chain, the Sysex messages started to work, with this chain:

Mastermind GT -> Voodoo Lab GCX (MIDI channel 16) -> Voodoo Lab Control Switcher (MIDI channel 16)  -> Boss DR-880 (MIDI channel 15 drums / 14 bass)

 

I replaced the DR-880 with MIDI-OX on the non-working chain:

Mastermind GT -> Voodoo Lab GCX (MIDI channel 16) -> Voodoo Lab Control Switcher (MIDI channel 16) -> HD Pro X (MIDI channel 2) -> MIDI-OX

I found that the messages leaving the HD Pro X MIDI out are modified, and the third Sysex command is being stripped.  For example, when I send F0 7F FA F7 from the Mastermind GT, only F0 7F F7 is being received by MIDI-OX from the MIDI out on the HD Pro X.  Again, everything works fine if the HD Pro X is not involved.  If you remove the HD Pro X and attach MIDI-OX after the Voodoo Lab Control Switcher, and you send F0 7F FA F7 from the Mastermind GT, MIDI-OX will see everything (F0 7F FA F7).

 

On the HD Pro X, the MIDI is set to Out / Thru (not Out only).  All cables have been checked and exchanged, and all MIDI cables are 5 pin as verified with a multimeter (except for the cable between the Mastermind GT and Voodoo Lab GCX, which is always intentionally 3 pin).  I looked in the MIDI Assign section of the HD Pro X, and none of the options are activated on any preset.  When the Mastermind GT boots, it sends a Sysex to the two Voodoo Lab devices on the same MIDI channel, so that they will know which one is which, but otherwise, no Sysex messages are sent.

 

Is there a way to resolve this, so that the HD Pro X isn't modifying data sent to its MIDI out?