So I see this most consistently against Big Bands, but I know some other characters cause this too. When combo-ing into Sweet Clarinet after a launcher, even without any additional input commands, the player Big Band will follow up the special move with an attempted air juggle. This juggle always misses, though. It seems pointless and it ruins attempts to continue the combo after using Sweet Clarinet. This doesn't happen with all characters, though, so I'm convinced it has something to do with certain opponents' hit boxes. I feel like this automatic air juggle should not happen. If I press Sweet Clarinet and nothing else, I don't want the game throwing in an air juggle automatically. I don't know if it can be called a bug but I would certainly like to see it changed.
Using Sweet Clarinet during a standard ground combo doesn't trigger this automatic air juggle. It's just after launching.