MIDI output differs for Drum Editor: no map vs any map

I am observing bizarre behaviour in Cubase 8.5 on Windows 7 64bit, whereby a Yamaha AN200 does not receive any MIDI notes when any Drum Map is set for it’s MIDI track. Clicking in the Drum Editor also doesn’t trigger a sound.

When the Drum Editor has ‘Drum Map: no drum map’ then the AN200 does receive MIDI notes and clicking in the Drum Editor does trigger sounds.

When that same MIDI track’s MIDI out cable is plugged instead into a different drum machine, whether a Drum Map is set or not in the Drum Editor, that drum machine receives MIDI notes.

I have tried removing the Drum Map from ‘Drum Map Setup’, still same problem.

I have tried editing the .drm file for the desired Drum Map to set all as I thought note length might be at play, still same problem.

Cubase is outputting MIDI through a Motu MIDI Express XT.

Very strange, hoping someone can explain what’s going on.