I have been trying to use Max as note input for Sibelius, instead of an external MIDI keyboard. So far it does not work.
An external MIDI keyboard works
When I connect a MIDI keyboard to my computer, I open up Sibelius' Input Devices preferences. I click "Find New Input Devices", and I make sure the device is checked in the "Use" column. Then I select a place in my Sibelius score to insert notes, and start playing on the MIDI. All the notes appear as quarter notes (or the note-length I selected). This is all good.
"from Max 1" doesn't work
What I want to do, is try the same thing with Max as note generator, instead of me playing keys. I try the same procedure: start up Max, click "Find New Input Devices" in Sibelius, and make sure "from Max 1" is checked in the "Use" column. I can send MIDI notes from Max, but Sibelius doesn't write them down in my score. Why? What am I doing wrong? The notes do appear in the "Keyboard" panel of Sibelius, so it is receiving them. (Note-ons and note-offs.) If I click notes in the "Keyboard" panel, Sibelius does write down the notes. If I play my external MIDI keyboard, Sibelius also writes down the notes.
Somehow Sibelius seems to notice a difference between MIDI input from a keyboard or from Max.
I am curious about what you think might be the exact problem or a good solution here.