Looking at the xml of an official DLC I see the ignore status is sometimes used in chords.

 

From what I understand an ignored chord will not count as a miss, even if it's not played.  I am curious, for what reason would an official DLC want chords to be ignored?

 

It's not just one DLC; I checked a handful of them and all of them had a note or chord ignored at one point.

Maybe they did that because their pitch detection didn't handle it well during testing? I think all we an do is speculate.