MIDITeensy4.1—USB MIDI not merged from AKAI MPK mini

[JeffAlyanak]

When flashed with the interface firmware and connected via a computer, I've confirmed that all ports work as expected, including the USB 'host' port. In that configuration I can take input from the AKAI MPK mini USB keyboard and have it output back out through any of the ports.

When loaded with the midimerge firmware, midi data from the AKAI MPK mini still triggers the LED, but no longer appears to be output from the DIN MIDI outputs.

Is this expected behaviour? A brief read of the source makes me think that all devices, including USB devices, are simply read and then output on the output ports.

Any guidance would be appreciated.

[Deftaudio]

Hi, I'm not sure why it behaves differently for merge/non merge code for USB host devices. You can take non-merge code and start uncommenting lines there to see there it breaks. That's what it makes merge code.
https://github.com/Deftaudio/Midi-boards/blob/master/MIDITeensy4.1/Firmware/interface_8x8/interface_8x8.ino