Notes from G2 trhu A3 work fine. Notes below and above produce no sound.
When the notes work - the "MIDI" light blinks:

When the notes do not work the "Key" light blinks:

Additionally, when I play F4 on the keyboard, it toggles the "Live devices" sidebar open/closed. And playing D4 toggles the arrangement/session view!!
It seemed obvious that I had accidentally programmed some oddball mappings, but checking both Key and MIDI mappings shows nothing to erase:
(Key Map empty)

(MIDI mappings empty)

How can I reset, reconfigure or erase this MIDI map?