I did had this problem sometimes. A forced rescan of the shared folder or a manual rescan of the album did not update metadata that are to be loaded from files. Have you tried a stop and start of Roon Core (server)?
In this very rare situation, I delete the album in Roon. Watch out, files will also be deleted on the share folder! Then I stop and start Roon Core, and copy back the deleted album in the share folder and force a rescan. Hope this will help.