Recent update description states this bug has been fixed but still doesn't show iTunes artwork of recently purchased/imported music to Traktor Pro 3 3.10.
Since Apple moved from iTunes to Music.app, it seems to store cover art differently. It's not only Traktor having problems showing the artwork.
I always use a script, to re-embed the artwork in music.app which works perfectly.
https://dougscripts.com/itunes/scripts/ss.php?sp=mxreembedartwork
There are tons of useful scripts.