The embedded images in Audible audiobook files are very low resolution (100x100px or less). For many years, I've been able to address this by downloading higher resolution (300x300px) images from Audible's website and use iTunes standard artwork function to substitute the better artwork. Admittedly, this functionality was somewhat anomalous, as - unlike other media file types - the alternative images were not embedded in the Audible .aa files but seemed to use separate image files, as occurs when artwork is acquired from the iTunes store.
However, this behavior seems to have been suppressed in iTunes 12.5.1 - all Audible-sourced audiobooks have reverted to the original lo-res artwork, and the usual Get Info > Artwork > Get Artwork function no longer works (the alternate image file can be selected and appears in the artwork tab, but it is not saved when the editor is closed). I've checked both read-only and permissions settings (which can produce similar symptoms with music files) but everything here is as it should be.
Has anyone seen the same issue, and/or suggest a workaround to it?
iPod nano (7th generation), Windows 10
