Here's a screenshot of some tests showing the issue.
Some clips display the label text on the audio track, some clips display it on the video track. Seems clip-specific -- see how clip MVI_2207.mov always has the label on the audio track, regardless where the video track is (it V1 or V2). I can't figure out how to make PPro always put it on the video clip, or what this option is called. Any ideas? Thanks!