IIRC pre 3.0 PlaylistNowPlayingIcon (if present) would override NowPlayingIcon in the tab header
Could well be, I don't remember.
I do remember in the old days 'now playing' resided in the playlist node. Later on it was upgraded to the library node.
That is probably the cause of this entanglement.
I just tried using both elements and switching their order around, but indeed now when both are present in the xml, both for the left Navigator panel and for the tabs, only the last one in the order of the xml is used.
So it is probably best to just consider "PlaylistNowPlayingIcon" as obsolete.