I found an issue that affect the musics in the Nether in minecraft 1.16 developpment versions.
I didn't know if it's a bug or not, but i think it must be reported.

When i play in the Nether, in creative mode (but i believe that other game mode are affected), i have noticed that Nether musics plays very rarely. I can play in the Nether for hours without hearing any Nether music (only ambience sounds), no matter if i travel across multiple biomes or if i stay in the same biome for a long while.