Does it actually connect though? I've had this bug myself a couple of times and I think I had just figured out the circumstances for it but for me it always missed. Due to being mid-air for a portion of the attack Big Band thinks he can perform an aerial combo so he attempts to execute it but it always whiffs.
Can you get a recording of this so that we can confirm if we're thinking of the same issue? It would also massively help the developers to figure out how to reproduce it reliably so that they can begin to tackle it in the code.
I'm also moving this to bug reports because while this thread is indeed about Big Band, it has nothing to do with combat strategy or his character, and Hidden Variable would never look in the character sections for bugs so you'd have very little hope of it being noticed.