I am trying to implement some data transfer mechanisms using CoreMIDI, but am having a lot of difficulties sending UMPs with type 5 (128-bit System Exclusive 8). I've successfully been able to send various voice messages like note-on/off as well as System Exclusive 7 (UMP Type 3) using both MIDISendSysex(:) and MIDISendEventList(:,:,:) but nothing seems to be getting through if I want to send a 128-bit message. If I send it to a MIDI 2.0 virtual destination directly, it works fine, but when I send it to the IAC driver bus or my MIDI-USB device, nothing gets through.
I have scoured the internet and CoreMIDI docs looking for a solution, or even just some more information but have found nothing. The messages themselves are formatted correctly according to the MIDI 2.0 specs. Is there something I'm missing? Any help is greatly appreciated.
