The bug:

Jukebox doesn't stop playing music when viewing advancements screen.

How to produce:

1. Place a jukebox.
2. Use music discs for this jukebox.
3. Press "L" to enter the advancements screen.

The music continues to play.

The music is paused.

If you return to the game after the music has finished playing, you can even notice that the jukebox is still sending out particles, but no longer playing music.