SugarCube 2.13.0 — controlling all playing audio and making it fade out?

From the documentation I see that there's ways to play, pause, and stop audio through the group IDs, but do the other commands work for those group IDs as well? I'm trying to fadeout all playing audio rather than hard-code the fadeout by hand but this:

<<audio ":playing" fadeoverto 3 0>>

doesn't appear to do anything.

Is the playlist method the only way to accomplish this?