There is a new setting in Picard.
I don’t know how your artwork is set. If it is set to pick Release then Release Group I agree it should have an image. (My own CD scans are in this RG… 
but the 2006 reissue with a black top. Had to put it on hifi and wake the neighbours)
(Edited: What was below is not relevant to this thread, so moved it to a new thread: Bug Report: v3.0.0b1 - full artwork download issues )