PAC and Bib Record displaying a different image than the Item Record

On those occasions when cover art images are inconsistent moving the order of the ISBNs in the bib record makes a difference. As expected, the cover image for the bib looks at the MARC coding and ignores the ISBN with the $z (indicating an invalid ISBN), which may be listed first. However, the item record pulls from the first ISBN listed, regardless of the invalid delimiter. Moving the correct ISBN to the top fixes the item record image.