Don’t know what the technical explanation is. The notes are certainly there, but Logic is partially based on Notator on Atari, and for what I know, the algortihms that determines how chords should be displayed be be 25+ years old… and whatever the reason is, Logic can’t do what Dorico and Sibelius and I guess every other music app on the planet does: always display four notes when we are looking at and hearing four notes. In bar 2 in th eLogic example, there’s a C and a Db (or a C# and a B#, depending of how you look at it), but Logic simply doesn’t handle such situation.
After one has learnt minor and major chords, the next three chords people lean is usually minor 7, dominant 7, and major 7 (Cm7, C7 and Cmaj7). These are maj7 chords; nothing esoteric here. But neither Logic, which I have used since Notator, or Dorico recognises such basic chords and displays them correctly.
Usually, if a chord consists of something which in theory could have been interpreted as C and C#, or D and Db… that’s not what it is. One wants, as much as possible (in all relevant situations) to display four notes with unique pitches, meaning that we usually don’t want to see C and C# notated next to each other in the same chord, or D and Db - and so on. That’s where Logic fails. It shows the note head for the C and the note head for what i falsely assumes is a C# on top of each other, so they appear as and, and not two notes. But this is a Dorico forum. 
Regarding hard quantising, that’s what I did, but I quantised note starts, not note lengths.
“If you don’t like the split stems then bring up Notation Options (Cmd-Shift-n or Ctrl-Shift-n), go to the Accidentals category and scroll down to the penultimate section, “Altered unisons”. Changing “Split stem” to “Single stem” will give you what I think you want.”
Thanks, Leo, What I’m trying to point at is that in order to display something as basic as a maj7 chord, we shouldn’t need know that stuff. D. should be intelligent enough both to recognise such basic chords, and to display them in a normal and expected way. And - if D. should choose not not do that (eg because that code isn’t written yet), there should at least be some code in there which would display the chord erratically, but in a normal erratic way. I think a good starting point would be to force D. to understand that if there’s both a C and a C# (or a D and a Db) in there, they shouldn’t be displayed as two versions of the same pitch, but as two pitches - of with an accidental, and one without. It should simply do what Sob has been doing for many years.
Regarding “a series of 12 chromatically-shifting chords with no other material”:
I only recorded all 12 chords to illustrate how the outcome will look for the different possible maj 7 chords. Nobody would compose music like that (I hope). But maybe someone would make educational material like that.
So I think it’s a fair test; just forget about the last 10 chords, only look at the first two. Have you even seen sheet music, anywhere, with a chord written like that? With C and C# next to each other, with an extra, diagonal stem - and one with a natural and one with a sharp, instead of eg C/Cb?
