Great Monday morning!
For now, the Now Playing widget seems to check for the cover at the very beginning of a song, am I right?
If you're listening to Apple Music (not locally saved songs) using Catalina (Public Beta) the cover is loaded a second or so after the beginning of the song. This induces the widget to show the iTunes icon all along, instead of the cover - hitting pause/play again refreshes the cover and here we go!
Maybe it could be useful to check a second time for the cover in case of an unsuccessful primary recovery of the artwork?
Thanks a lot, have a great start into the week!!