Hello Carl,
what exactly do you get as a result? Does your Octopus react to the SYSEX stream? Does the Matrix fill up to about half? Does your Program LED blink? Red or orange?
One first thing to try is to reduce the speed of the MIDI Sysex stream. Other than that maybe a MIDIOx user can jump in – the settings for my SYSEX librarian on OSX are "Pause betwenn played message 120ms" with full transmission speed for the interface, which is an Elektron TM-1.
Hope this is of some help.