Because during the development from 21.0 to 21.1 it was discovered that information (or I) is pointless if there is no information at all, this option was removed from the core. Unfortunately, I no longer have the option to edit graphics because this function was also removed along with the information. This only affects music videos for which no CDs from the artist are included in Kodi. One possibility would be to change the entry “set artist thumb” to “choose art” in the context menu.