Album Artwork Not Showing

If the artwork for some of your albums or songs is missing

1. On your Mac or PC, open iTunes.
2. In the upper-left corner, click Music.
3. In the left sidebar, click Albums.
4. Find the album with the missing artwork, then right-click or Control-click it.
5. Click Get Album Artwork. To select more than one album, hold down the Command key on your keyboard and click additional albums.
6. iTunes adds the album artwork.
7. From the menu bar at the top of your computer screen or at the top of the iTunes window, choose File > Library > Update iCloud Music Library.
8. After iCloud Music Library has finished updating, open the Music app on your iOS device.
9. Find the songs that are missing artwork, and remove the downloads from your device.
10. Tap the download icon to the right of the song to download the song again from iCloud Music Library.

You need to:

remove all downloaded music in the Music app

(only if you downloaded it from Music to iPhone. if you only added it to the library ignore this step)

• switch off iCloud Music Library in both iPhone settings and iTunes
• backup iPhone to computer or iCloud or both through iTunes
• restore iPhone to factory settings through iTunes
• restore iPhone to the backup though iTunes
• turn iCloud Music Library back on in both iTunes and iPhone settings
• Update iCloud Music Library through iTunes
• sync iPhone through iTunes

Open the Music app on iPhone - all the artwork will be back.