Amazon links in the "Available at" area aren't displaying, but other shop links work. Example, Sonic Generations OST:
http://vgmdb.net/album/29979 (Amazon is not listed)
http://vgmdb.net/db/album-submit.php?do=link&id=29979 (Amazon link is there)
Noticed it on the
Final Fantasy XIII-2 OST as well.