MC Version: 1.20.1
Mod Version: 3.1
Cupboard Version: 2.7
Forge Version: 47.3.0

A good example is the Ender Dragon. Unless the Ender Dragon flies near me, he is completely silent. I also cannot hear the Elytra woosh sound at all. I can't hear distant explosions. I don't know exactly what the distance is.

In a modpack, there are some other distant sounds that I was unable to hear, such as Yung's Better End Island entrance noise (the 'gonging' noise that plays the first time you enter The End), unless I got within ~10-15 blocks or so of the noise source.

This issue occurs even when Biome Music and Cupboard are the only mods loaded.

fixed in 3.3