This is a bug with the way “Edit → Labeled Audio” works. While these commands run correctly when only the Label track has selections, none of the commands run at all when other audio tracks are included in the selection. The following documentation (at the very end of the page, under “Example 2 - selection in the Label Track and some Audio Tracks”) explains that partial track selection will limit the Labeled Audio commands to executing only on the selected tracks:
Start a project and add a couple of audio clips to two different tracks.
Add a Label track, and add some labels that overlap with the audio clips.
Select the entire Label track, and choose Edit → Labeled Audio → Split, and notice that the audio clips in all tracks get split on the labels. Good. That’s what’s supposed to happen. Undo.
Now, select everything in the Label track, along with everything in just one of the audio tracks, and perform Edit → Labeled Audio → Split. Nothing will happen.
It appears that none of the commands execute at all unless only the Label track has any selections on it. Trying to reproduce the example in the documentation produces no results when using these commands.