I am having probably the exact same issue with my Native Instruments M32 keyboard. Driving me nuts. Already completely reinstalled and updated everything multiple times, but the issue remains. I selected DDJ-1000 as audio interface and everything works fine in Ableton, except for the midi input. There seems to be midi input coming to Ableton from the M32 as the small square next to midi flashes in Ableton every time I touch a key, but I can only play notes for a second. After this the small square midi-indicator still flashes with every press, but no new notes are playing in Ableton anymore.

