iPod Nano 6 not displaying album artwork?

Hey, iPod’s pretty ancient now but I still enjoy using mine from time to time. I’ve been using my old iPod Nano for about a week now, but some album artwork doesn’t show up on the device? It shows up perfectly fine on the iTunes application, but not on the iPod itself. Not a serious problem, it’s just a little annoying. (Pics below)

The songs I added in ~June last year are fine, but the art for more recent songs I’ve added aren’t showing up. I’ve tried syncing and looking up other answers, but nothings helping because it’s such an old device haha. Thanks for reading, hopefully I can find a solution to this 😭 (apologies if this is badly structured/tagged, i’m not familiar with using this site haha)