Hello
I am using MC17 but I have always been facing this problem with version 15 and 16 of JRiver concerning cover art.
For some of my files (maybe 3 or 4 %) it is simply not possible to store a different cover art as thumbnail than the one selected automaticly during the very first importation into the Library.
For exemple if I have an album with 4 songs and 3 cover art: Front.jpg - Back.Jpg and Inside.jpg
It could prompt the Back.jpg as the album thumnail
If I try to change that by Cover art => select from file and pick the Front.jpg image
it never never replace the wrong cover art by the one I have selected... unless I unchecked the "also store in image file" Option in the Tools => Optin => File Location for cover art.
Even when I try the following command :Covert Art => Remove Covert Art => Do you want to permanently remove cover art from your disc
1) it does not delete any cover art in my folder
2) I still end back with the wrong Cover Art EVEN after having manually removed the wrong cover art from my folder
3 ) When I select an audio file and right click on property => audio property I have the correct covert art prompted BUT in J river the thumbnail (LArge and small) is always wrong