For some reason, about 95% of the cover artwork normally shown in the Artist or Album pages and their click-down song lists in the ‘On this Mobile Device’ category have recently vanished - sometime over the last month or two I guess. The artwork is still visible on the actually player screen when you listen to any of the songs.
All of the files are MP3 and correctly ID3 tagged, and they all displayed fine until recently. This problem had occurred on both of the Samsung phones in our household, where files are stored in a Music folder and its subfolders on the local SD Card on one device (Galaxy A40), and in internal memory on the other (Galaxy A70), with relevant access permissions granted. Both phones have updated themselves from Android 9 to Android 10 relatively recently, in case that’s related.
[Edit: seems OK on my Samsung Tab S2 tablet running Android 7]