OK, that is pretty much what I would have done. And you’re right it doesn’t give the expected result. But it seems to be related to the Function at the bottom being set to Select. If for example I change the Function to Transform and add in the bottom section for it to change the MIDI Channel number to 3 it works as expected - none of the non-Selected notes change Channels and for the Selected notes every other one is changed to 3.
So you have the general concept correct but in this specific case (selecting from only the already selected) it doesn’t work. Not sure if this is the expected behavior or not - but it seems wrong to me. I’ll play around with it some more. As a workaround you could remove the ‘already selected’ criteria so it will work on all the notes. Then cut up your MIDI Parts so a Part only has Notes you want to process or only notes you don’t want to Process. But that is pretty ugly & not always possible.
If you are doing this to accent specific notes there is an alternate approach where instead of basing it on every other note you base it on the position within the bar. Take a look at the attached LE Preset which increases the velocity +15 for Notes on beats 1 and 3. FYI this works fine on Selected Notes only. I have another one that increases beats 2 and 4 by +8. Stick those in a Macro & add as a Key Command and you get one-key accenting where any notes not on a beat (or within the range you set) will be at the original Velocity and the beats accented accordingly.