Midi Mapping

I use an M-Audio Oxygen 49 midi keyboard to input notation. In Musescore 3.62, I assigned various buttons to note duration values (sixteenth, eighth, quarter, etc.) and "dot" and rest. Works great! Right hand entering notes, left hand choosing time values!

However, with Musescore 4 (and 4.01), the keyboard part works fine to input pitch, but when I go to Edit / Preferences / Midi Mappings to assign the buttons to note durations or any of the play/stop controls, Musescore interprets every button as CC 0 . So I can't use my midi keyboard to select time values or playback options. What am I missing?