With shuffle enabled, the tracks disappear from the Now Playing list as they play. With REPEAT enabled, right now, they all disappear from the list until there's only one track left.
When it has to play the list again because REPEAT is ON, instead of loading all tracks in the Now Playing list again, it only changes the one track that is left in the panel for the new playing track.
I don't see a strong case for the Upcoming Tracks panel to be available for when shuffle is not enabled
Then why not having it only when shuffle is enabled and when shuffle is disabled, it should go back to Playing Tracks automatically.
What I'd like to have, is a button I could add to the Header Bar to enable on disable Upcoming Tracks. With a way to tell me if it's ON or OFF.