When switching from creative mode to spectator mode, any game music (not records) cuts out. This may be intended behavior, but is very annoying when frequent gamemode switches are needed.
Steps to reproduce: start a world in creative mode, wait for music to play, then switch to spectator mode.
I'm very sure this is intended, the music is bound to the gamemode, so it stops the music from playing because it should not play in the gamemode you switch to.