how to get USB midi working

Hey there. I'm having an absolute devil of a time trying to get the deluge working with USB MIDI.

It's a brand new Deluge (and i'm new to deluge so maybe this is an idiot error, but could also be the unit perhaps - as i've not had usb midi working on it yet).
I've put it on Community Firmware 1.2.
I've plugged in my USB keyboard to the deluge which is a Medelli MK49 (a very dumb keyboard it literally just has a USB port, no other connectivity).
put the Deluge onto a 9v center-neg wall adapter
I turn on the keyboard with the passed through USB power.
I turn on the deluge. (have also tried turning the keyboard on after, same outcome)
I then hit learn + an audition key, which makes the audition keys flash.
I then hit a key on the keyboard, and... nothing.

What am i missing here ?
Other info:

• the cable is a USB type B to A, with an A to C adaptor on it (the keyboard is usb-c)
• this cable i've used before with this keyboard direct to my mac so i know thats ok
• the medeli 49 keyboard i've never had an issue with - usually just plug it into my mac and no issues.
• i tried connecting the deluge direct to my mac, and it shows up on the "ioreg -p IOUSB" command
• i couldnt get the deluge to trigger off notes passed to it from bitwig, or vice versa, but it did show up as a device at least