@bolandross
I've had the situation you describe since I first installed BIAB, two years ago so... not Big Sur related (at least not on my case).
At the time I searched the forums but couldn't find any reference to it so I've assumed it was either something to do with my setup or some eventual UI laziness bug that would be corrected in a future patch.
Despite all the struggling with my setup I couldn't find a fix for it (and I don't have SoundFlower, Audio Hijack, Loopback or any other similar software installed on my Mac).
Meanwhile, two years have passed and I've just learned to live with it but... it would still be nice to have it fixed.
Mac mini (Late 2014)
CPU: 3 GHz Dual-Core Intel Core i7
GPU: Intel Iris 1536 MB
RAM: 16 GB 1600 MHz DDR3
I'm not sure that this is the same problem that the OP is experiencing.
- When you play a song, is the chord highlighting EARLY or LATE?
- What Band-in-a-Box version and build are you running?
- What OS do you have?
- How do you have you speakers connected to your Mac?