When you double-click on a song to play in track details view, and then double-click another song, the speaker icon stays located at the former playing track(s):as i am sure you would appreciate, if that was something that ordinarily happened it would have long ago been reported and fixed. So for now i am putting this down to "something about your machine" but if others report the same or you are able to provide a specific set of steps then i will investigate further
(Rostropovich is actually playing here)
Of course I can't have any reliable notion about other users noticing this or making the effort to report it.
I thought I'd try this. The speaker icon seems to switch as expected when I double-click on a track and then click to switch to the next track. I have Prefs | Now Playing | Playing Tracks List | when tracks are playing = Queue Next and so the current playing track continues to play when I double-click another track.
I did notice something. If I change settings to Prefs | Now Playing | Playing Tracks List | if playback is stopped = Play Now, and I double-click a track while nothing is playing, nothing starts to play. Seems like "Play Now" isn't taking effect when nothing is playing and I double-click a track.
I don't think this helps hiccup but....