Some of artwork isnt updated. I pressed update from Musicbrainz icon only.
When I pressed update from discogs Album art from Animal Rights changed “blue status” to standart and images were changed like the only one not changed ( see screenshot )
In Rare: The Collection only first was updated.
Looking at the screenshot all the other songs in rare already have three pieces of artwork, whereas I expect track 1 didn’t have so when you update the others don’t get updated probably because they already have artwork which is higher resolution then what is available.
For Moby it is probably that the other also have songs that are higher res artwork.
If you always want to overwrite you can change this in Preferences/Musicbrainz/Format/Artwork