A:B and C:D buttons do not relate to the inputs with pickup machines, they relate to the functionality, MIDI note 61 acts as the A:B button and 64 acts as the C:D button does, refer to One2 diagram in manual for pickup machines and look closely at your inputs in the recording setup menus. Never explored “easy record”, or whatever, so no idea how that may influence anything)

Assuming MIDI is coming through correctly (i don’t think Note offs are needed) then it sounds odd that the button behaviour does something different … use a monitor object in Lemur to see what commands it’s actually putting out

Edit: A:B button behaviour ‘replication’ is more nuanced, see below